Sitting is the new smoking. It's now responsible for a quarter of deaths. Since death is inevitable, Calvin has decided to master the art, along with Hobbes. Lets take it to the next level. Sitting against the wall squats. 

Most of us exercise the art Calvin has perfected. 

Time to Get Off Your Arse (GOYA) now. Remember, if running is your love, strength training is your mother-in-law. Love her or hate her, but you need impress her to not get in trouble with running.

Wall squats are very useful for all, runners or not. You don't need to squat all the way down from the beginning. Just get started. Start even with 5 sec reps, 5 odd reps, 4-5 times a day.