A splendid idea and one I'll follow as soon as I live elsewhere.
Edit; or do something minor like stretch my arms ten times or whatever. That's less likely to disturb others in the room than jumping to the floor for push ups.
I once stopped smoking this way. 10 push ups when I felt the need of a smoke, repeat if the need was still there. Had to make 6-8 rounds at first, but it worked in the end.
When you forum while playing MMORPGs in your browser like me or just post a lot it can make a difference and who said the challenge was set if you want to you can choose to do 25 push-ups per post.