OP
You can put a stability ball between you and the wall too. It’s a little easier on the wall than a skateboard!
But I'm looking for an excuse to rip that wall out too..

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You can put a stability ball between you and the wall too. It’s a little easier on the wall than a skateboard!
If you have no equipment handy do bodyweight squats for the best use of your time with wall squats previously described to then target your quads. Lunges are great too but my knees are shot from lifting heavy weights and sports so I cant do them.