I walk and walk up stairs whenever I can. I also try and take a walk during my lunch breaks, which is good to clear the head and sort out the eyes from staring at a computer screen all day.

Also sometimes I have an hour conference call with the USA on my own in the boardroom and almost always do a bunch of push-ups, sit-ups and chair-dips during the call. So far I have never been caught breathless when a question is directed at me, and as long as we keep it VOIP only and not video I should be fine. The other day I asked security if there were any CCTV cameras in the building and lifts. Fortunately there aren't as I tend to squeeze in 5 air-squats or dips (on the corner rails) in the lift going up and down 5 floors. Doing a dip against gravity is quite effective actually.

One winner for me is when I am working into the night alone, every 2 or so hours I take out my pink CAT5 network cable jump-rope I made, and do a few rounds of skipping, drop down for a few push-ups and carry on with my work.

This all seems to work for me.

We have an exercise of the day. Every thirty minutes you stop and do 25 pushups, 25 squats, one minute planks, etc. It really helps!

I only email coworkers who are in the office if I need a record that the conversation took place and I never use the phone or chat system. That means that if I have a question, I have to get off my rear and go ask them. Not feasible in a lot of corporate environments, but good in my smallish company.

I get up and take small breaks every hour or so. Refill my water, make tea, use the restroom, whatever. I try to take a few extra steps whenever possible (i.e. take the long way around to my destination). I could probably take some dumbbells or kettle bells in to get small bursts of exercise in those periods if I wanted to.

I'm working on hacking together a standing desk so that I'm not sitting all day. I'm trying to come up with something I can adjust fairly easily, though I think I'm just going to have to take a leap and come up with something not adjustable. I'll get used to it eventually.

The place I work is pretty casual, though. I could probably wear my pajamas into work and nobody would give me a second look....

Also, if you're the one in charge of the farm, it's much more intellectually stimulating :) (says the farmer's granddaughter).

I commute on the train/bus which involves about 30 minutes of brisk walking per day. This helps as a minimum, I would like to get more exercise than that, but it is good to be forced to do that much every day. I also make it a point to go outside at least once a day and walk, like take the long way walking to get lunch or something.

If it is not too cold, I do my kettlebell routine on the porch at home, which also gets me some fresh air and nature.

All of that said, this is a fraction of the exercise and fresh air that I would like to get, but that is life these days. One day I will find a well-paying job where I can be outside most of the day...

2 hours commuting a day by train - I seldom sit down, sometimes doing one legged balancing or standing on tip toes (all while enjoying media on my tablet) My school is on a hill, gotta walk up the hill and down again from the train station - avoid the bus. As a teacher in class, I always walk around the room, never sit, do some deep squats behind the seated class sometimes while they are working. When a student needs help, I always squat (with good form) down beside their desk. I use the squat toilets in the bathroom (benefit of living in Japan). As you can see I do a lot of squatting on a daily basis! Always bound up stairs, never dawdle up. While walking down an empty corridor with no one looking I have been known to lunge walk. I hand crush steel beverage cans (usually other peoples!) before discarding them.

Exercise is everywhere, all the time, if you just think about it more.

edit: also carry a "handytrim" ultra compact exercise tool in my bag. Seems like gimmick but they actually do work, relaly get the blood flowing in your arms and shoulders. http://www.youtube.com/watch?v=R-LYNWFdLKE&feature=related

I am lucky enough to have a corporate job in NYC so I get to go out and walk for an hour during lunch and try to walk home as much as possible. Like Banded Girl said, I try to get up to have conversations with people instead of sending instant messages but I can definitely get sunk in my chair. I try to do a lot of stretching too, especially hamstrings so it doesn't feel like my butt is atrophying in my chair!! I grew up on a farm and landscaped during summer breaks at college - I loved that physical lifestyle, and definitely miss it. Glad you got to experience it.

I walk to school, walk to the store, walk when I need to get somethings and take 5 min walks whenever I get restless. Works for me.

The desk job always results in degeneration. Start an orchard if regular farming isn't enough.

I work at a standing desk and hit the gym at lunch every day. I also volunteer to change the bottle on the water cooler (man, I can't believe how dorky that sounds...).

Mark Sisson has TONS on this topic: http://www.marksdailyapple.com/

I'm not in corporate America yet, but going to conventional school I experience the same environment. To offset sitting, when I'm at home or when I have a break, I stand. I stack books on top of eachother to bring my laptop to standing-appropriate height so I can stand anywhere - you could stand all day if you cheaply build or makeshift a standing desk.

If I want to go get something, I walk - I don't beg my carred friends to drag me around. Take your lunch hour for physical activity; you get bonus points if you convince your co-workers to play a pickup game of futbol with you.

If you can commute to work in anything but your car, do so! I walk over four miles a day in commute, and while it sounds like a long time (one hour and thirty minutes on average), it doesn't feel very long. My walk awakens me for the day ahead and mellows me out on the way home. I would give up my resistance training before walking. Biking is a wonderful form of transport also, though I tend to use too much glucose as a fuel while biking and so prefer walking.

I wish I had your former job....

The quick answer is you probably don't. Unless you work out a lot after hours, you'll probably never have the same muscles as you did during the farmwork. You just don't get the same stimulus to your muscles. You can do some things during the day to mitigate things depending on your location (subway, walking, biking, etc). Some people like Dave Asprey say they eat 4500 calories a day and don't exercise and keep their muscles. Not me...

When I got my first office job, a coworker told me about "the spread." Take a look at your coworkers and see how many of them have smooshed, spread out rear ends, sometimes twice as wide as the rest of their bodies. My coworker attributed this to them sitting all day. This has always been great motivation for me to get up outta my chair! 8)

I have to agree with James in that working in an office won't allow as much activity as working on a farm does, just because of the nature of the jobs. There are, however, some great ideas posted for staying active while at work.

I use the time at my desk to work on mobility exercises/stretches. For instance, I have plantar faciitis and I have a golf ball that I roll around under my feet. I also try to stay focused on my overall posture and body tension. Like many office workers, I tend to hunch my shoulders so I try to keep that in check. I also clench my jaw habitually, but I have a reminder to help me loosen up. Of course, if I wasn't stuck at my desk, most of my flexibility/tension issues wouldn't exist...8)

I try to get out of the office at least once a day and walk around outside. It takes maybe 10 minutes total to get downstairs, lap the two buildings that make up our office "park," and get back to my desk. I also eat my lunch outside when it's feasible.

As others have mentioned, I make an effort to take breaks where I'm getting up and walking around, like filling my water bottle or talking to coworkers.

I think you're starting off with the right attitude: you have to be aware of the lack of activity that's common in an office and make an effort to up your own personal activity.

http://www.amazon.com/FitDesk-Compact-healthy-computing-gaming/dp/B003JTLJFY

gotta love that 5th picture.

Or if you wanna be more subtle about it, http://www.amazon.com/Isokinetics-Inc-Brand-Pedal-Exerciser/dp/B000KDWA82

I walk 25 mins (2 miles) each morning and evening between my house and railway station, plus the distance at the other end to the office and around the underground. I also go up/down approx 130 steps 2 or 3 times a day (I work on the 3rd floor). Plus random walking about to get coffee/going to meetings and so on.

Random movements....I'll drop and pound out a quick 20 pushups or some squats or pullups or dips. Whatever is around. I like to mess around on a balance board also. Good proprioceptive work.

I commute by bicycle, and if the weather isn't horrible, I walk instead of eating lunch. There's nothing like seeing your bike out on the rack at the end of a bad day at work- unless it has a flat!

The program WorkRave really helps with computer-related stress. The program reminds you to take short micro-breaks, and longer rest breaks periodically. My eyes used to feel very tired at the end of a workday, but now it's virtually never an issue. I might just stand for a bit or close my eyes on a microbreak (I have those set to 35 seconds per every 10 minutes of computer interaction) and walk around, use the bathroom, jump up and down or hit the stairs on a rest break.