If you go to a gym they have different weights for different parts of your body. Find the leg section, and just get going. If you don't have access to a gym, then just different yoga poses and squats can help.
walking lunges, deep squats, straight leg deadlift, leg extensions, bicycling, running up and down stairs, stairmaster, calf raises, getting in a deep squat5 and holding it as long as you can 15x, endless possibilities. The best are the main three though-, squats, lunges, deadlifts.
You can have your back against the wall, hold onto a weight, and do squats. That's like crunches for legs. Make sure you hold them for some seconds though. The longer, the better. I hate having to count to 30 (3 sets of 10), so I hold longer to do less of sets.