@JessTheUnstill Tangential perhaps, but I used to bus to Nederland, Colorado from Denver, walk to the trailhead at about 8,500 feet to the Continental Divide at 11,000+ feet. I was in good shape, and always felt chuffed that I was up to that hike. But somewhere along the trail, some guy in shorts and running shoes would always come pounding up or down past me as if he were jogging down a suburban street. There's always someone better than you. But they get the knee replacement before you do.