My gym membership is basically a $39 a month donation to a building I drive past and wave at like an idiot, so you're already doing better than me. Honestly your buddy is half right, any extra movement helps, but the walk is doing more than he gives it credit for. Eight blocks plus a stop every single day adds up to way more steps than two shameful treadmill visits, and the fact that your resting heart rate dropped says it's real. The trick is it only works if you actually keep doing it, so the "running late at 8" mornings are the real enemy here, not the gym. Maybe keep the gym for the days it rains and treat the walk as your main thing instead of feeling guilty about it.