How do you consistently increase the amount of exercise you do?

I will wait about a week or month doing the same routine. After that time has passed and I feel good about it, I'll add a little more or take it to the next level.

Slowly, and a little bit at a time. Turn that 10 minute bike ride into 12 mins instead of 20. Then once you're comfortable at 12, try to go 14 or 15. If 1 extra minute is all you can master, pay yourself on the back and maintain 13 minute rides until you can push a little more. Every little increase builds confidence and endurance. You can do this!!!