If my knees are happy about it and I’m getting back into excercise ,I find just the everyday squats super.
The reason being if I choose to go on long walks or runs I feel like bounding because it’s that much easier …and especially going uphill.
I kind of do my own modified calenetics that works on deep muscle giving strength and flexibility .And the great thing about it is I can incorporate into my everyday life throughout the day.
While I’m waiting for something I’ll stretch ,then it all ads up.
My favorite excercise is gardening,I enjoy the digging and shovelling ,bending etc, so it doesn’t seem like too much effort,I don’t even think about it but just get on and do it.