Played for 45 minutes, which I really shouldn't do all at once. Really.
Tendons incredibly sore. Didn't realize how sore until I stopped playing.

SET A TIMER again.

Thumbs have a joint in the middle and they can actually bend there; you do not have to put your entire wrist and arm into it.

PRACTICE BENDING YOUR THUMB.

Was actually able to get 4th fingers...er, make that pinkies, to behave during faster scales, yays! Keep practicing that.