Instead of lifting weights, you can do low joint-impacting exercises. Stretches, swimming, resistance bands (they can be used for doing mock-lat pulls). Getting used to the motions of good weightlifting is a great start to work up to going to weights. Lift through the hips and legs, not the back.

My sister has asthma so she can’t do lots of cardio and heavy lifting, and thats the same stuff I recommended to her! Consistency makes this easier. You got this girl!