The Wall Sit
Lean up against a wall and sit back so your legs create a 90 degree angle with the floor. Good, you remember geometry. When it starts to burn, just pretend your balancing easy mac on your thighs and all the pain will begin to remind you of imminent satisfaction, rather than your evident inferiority. Plus, let's be real, this wall sit is probably the closest you've been to Wall Street since your dad made you take an economics class in college.
[Photo via @themichellesenner]