"Build muscle fast" = just because! I'm an old, weak fart and I wish I didn't need to defer as much to my 24 year old son in matters of strength when we're doing projects - how's that for a warped goal! I actually would like to have more muscle, but it's not a big deal. I just tend to dive into things with intensity - if I am going to do it, I want to do it well.
I plan to dial it back - less weight, more reps. Yesterday one of my knees felt slightly unhappy from the leg extensions, I felt like I had thunder thighs all day long, and I don't want to start skipping the gym because I dread it.
I also am biking more. 57 miles solo today, New England rolling hills, 14.2 MPH average despite about 8 stops to adjust the saddle.
Thanks for all the observations and advice.