You’re absolutely right.

Basically, anything that gets the heart pumping faster and the endorphins going, but doesn’t require a lot of thinking and complex action, can get the kind of mental benefits I’m talking about here. I lift weights and do bodyweight exercise, and it gives me a great energy boost — both mentally and physically. However, those kinds of exercise don’t allow me to do 2 main things that running (and I’d imagine biking) does:

1. Go on a form of autopilot for a while, where my mind is free to roam
2. Keep a sustained level of relatively stable exertion, which basically steadily supplies the exercise-related neurotransmitter level increase.