I once told someone I could tell how I was doing mentally by my last mountain bike ride. If I’d taken an aerobic ride on fire roads — one where I could go relatively fast without paying much attention, one where I could let my mind drift — I was doing pretty good. I was still doing pretty good if the ride was half fire roads, half more aggressive, aggression-relieving singletrack. If the ride was all singletrack, all aggressive, all manic, all fast, well, then the bike was saving me $100 an hour on a leather couch.