Overhead squat 1-1-1-1-1 reps
Front squat 1-1-1-1-1 reps
Back squat 1-1-1-1-1 reps
Try to increase the load on each of the fifteen sets.
*Remember to use good form with a strong body position for each movement.
Here is a good video addressing the importance of proper head positioning:
Local 1592 Fitness Training 
Paul Mc:
OHS: 95 115 135 155 175
*I tried to keep armpits forward, which is new, which made it uncomfortable
FS: 185 205 225 235 245
*Felt good
BS: 255 275 295 315 335 350
*Felt good