I've got a friend who's never been active her entire life. She's easily demotivated and has the usual back and knee pain so low impact would be appreciated.

There should be no too complicated moves there, even slow lunges could be overwhelming at first. It should really be very easy and offer accommodations. Maybe a length of 5-15min optimally to ease her into it.

I recommended some stretching workouts first, so she'll do something really relaxing to get in the right mindset.

I want her to try it out herself and figure out herself if she can go on from there. But as I said, her motivation is really low and little confidence so it should be really accommodating.

Thanks a lot!!