Hi Margaret — I'm sorry I'm just now seeing this! And very sorry to hear about the knee issues you're experiencing. How do your knees feel when you try a bridge? It's a nice way to strengthen the quads and glutes/hamstrings (and the core!) but doesn't put as much pressure on the knees as a squat. If your knees feel sensitive when you try it, you can always walk your feet out a few more inches away from your glutes. I described them here, with a gif: https://elemental.medium.com/bare-minimum-moves-for-people-with-no-time-to-exercise-309ea63a1385

Editor and writer. Past: Elemental, Real Simple, Refinery29, SELF. Certified personal trainer; prenatal and postnatal exercise specialist. Cat & person mom.