I have a problem with my knee where it hurts a lot when my leg takes weight (for example, I can do one-legged squats with one leg but not with the other because my knee hurts too much). This knee hurting when the leg takes weight means that the muscles in that leg are a lot smaller than the muscles in the other leg.
When I went to the physiologist for a solution, I was given a set of exercises, including leaning against a wall with my feet 30cm away from the wall, shoulder-width apart, and slowly skidding down the wall until the angle between my shins and thighs is approximately 90 degrees (squats against a wall). One very important thing I was to ensure was that I applied the same amount of force to each leg.
Upon doing this exercise, I realised it was very easy to allow the strong leg to do all the work and neglect the weak leg. After a few days of doing this exercise, I realised that my weak leg was not benefiting from this.
My weak leg is not strong enough to do exercises of this nature by itself, so I can only do exercises that use both legs. How can I ensure that I am working the muscles in each leg equally? I am not looking for diagnosis for my knee or a set of exercises to strengthen my leg, but a way to make sure that my weak leg benefits from the exercises. Note that the exercises do not hurt my knee at all but do not benefit as my strong leg 'takes over'.
tl;dr summary: how can I ensure that I bear the same amount of weight on each leg when doing leg exercises?