Compound exercises are the best:
- Stiff legged and normal deadlifts (will take care of those hamstrings and lower back)
- Squats (Your quads will finally have that power to take you up that hill!)
And don't neglect the upper body:
- Bench presses (incline, decline, flat) dumbell and barbell! Work out that pec and tricep!
- Upperback (such as pull-ups) and biceps.
Muscle mass is a must