Best I ever feel is when I'm walking 4+ miles daily. The phenotypic human body (not to dismiss any individual's disabilities or idiosyncracies) is top-to-bottom built to walk long distances, and bipedalism is an older trait of our evolutionary lineage than a lot of the other qualities we take as "human."

This really stuck with me from studying comparative primate physiology as an undergrad. The human leg and foot is a total outlier in comparison to any other primate's limbs. Our bodies are incredibly specialized for walking and running.