Staying mentally and physically active in retirement

Hello everyone! I'm 64 and about 5 months from retirement. I guess 65 is considered early retirement these days :-) Not by me! My only real concern/apprehension is that I will have a hard time staying motivated and active. We all know how important it is to stay active, both mentally and physically, and most of us know friends or relatives who are suffering the consequences of NOT doing this. One family member (long retired) once said, "Doing nothing begets doing nothing". I don't want that to happen to me!

There's a lot written here about "doing nothing" and how it can be great (at times), but we all know how toxic it can be if you make a lifestyle out of it. It would be great to hear from some of you who may have struggled with this and successfully overcame it.