Yoga, this guy has a great story of his own health issues (a former "wrestler" as in the entertainment stuff on TV, which is not exactly a safe thing).

Also, just get out and walk in a park. Start slow. Make it measurable (like in time).

Frequency matters more than just about anything else. Doing a little bit here and there through the day can make a world of difference.

Can you take a mid-day break and walk, even for 10-15 minutes?

Get up and walk around your office for a few minutes an hour. Better if you can do this every 30 minutes... Just get up. Sitting is bad juju.

Don't forget your vision. Look outside, to the distance, for a minute or two occasionally. This helps the muscles that control your eyes (like any muscle, they don't like sitting still).

The hardest part of any of this is the mental choice, the commitment to make a change to a new routine. I've always struggled with this, but have worked with people who were great at it - so I think of them occasionally for motivation. One guy would be at the gym at 5am,every day... In his 20's - and then come to work and manage a team of people. A middle-aged manager (in his 50's) I worked for would go for a run on his lunch break.

Oh, to be so motivated.

You can do this. Just mentally reward yourself for any little thing you do. Keep an internal dialogue about the positive aspects of doing things that help, to counter the "fuck I don't want to do this" voice.