Couple of exercises specific to the legs and butt. I do these two together and basically do 20 squat jumps (1 + 2) then go straight into alternative squat jumps (3 + 4), then in between sets have a 20 second rest... Try and make it to 3 sets, If its a bit too challenging just work your way up to it. You should see improvements pretty quickly with this exercise if done consistently.
Tips for 1 + 2.. Squat as low as possible but don't let your knees come over your toes. When pushing up, squeeze your bum cheeks and jump as high as you can, spotting your landing back into a squat... Repeat continuously.
Tips for 3 + 4... Basically the same as the squat jumps but you're alternating legs. Don't let your knees come over your toes and explode upwards when alternating legs, spotting your landing into a lunge position on your other leg. Engage your stomach muscles for stability and don't forget to breathe (in both exercises)...
We often underestimate the power of the breath especially when you're fatiguing. Stop for a minute, focus on slowing your breathe down, inhaling for 4 seconds and exhaling for 4. Doing a light stretch in between sets wouldn't hurt either as this can often re focus the mind, balance the blood and re energise the system. Give it a go and give me your feedback!