Over the long term, the only way to keep up with an exercise program is to find something you like to do. If you enjoy riding, you'll do it because it's fun. If you don't much enjoy riding, it's easy to find excuses not to do it.

Do you enjoy it? Then pump some air into that tire (in fact, check the pressure in both tires--they do lose air and need to be topped off regularly) and go for a spin around the block. If it goes flat, you won't have far to walk to get home. If it holds pressure, then you can venture farther.

If, ultimately, you don't enjoy riding enough to want to do it, then for goodness' sake, don't feel guilty about it. Try something else instead. Biking should be fun, not a chore.