SQUATS and more squats.
Cossack Squats, One legged squats, air squats, and finally:
BACK SQUATS 5×5 @80%
BOX SQUATS 5×3 @80% (squat to and sit on a parallel or slightly below parallel box/chair/platform)
Conditioning:
3 rounds of GHD sit ups and Hip and Back extensions 10-15 reps each.