Buy in: Tabata downdog progression. Get your legs prepared to move heavy loads by grinding your gristle out on some pvc. If you have poor mobility and you don't do anything about it you're a dope. You're better than that. Come on!
Back squat: Complete 10 sets of 2 reps. If you aren't interested in getting stronger or burning fat, keep it really light and try to finish in roughly 6 minutes. Otherwise, put some weight on the bar and go to war. Ideally you load progressively and work up to 5-6 sets of pretty darn heavy weight.
And remember... the weight on the bar may change, but the standard is always the same: to get the crease of your hip below your knee. If you aren't sure ask. If you're afraid you may not like the answer, then you know the answer.