I've found that simply incorporating a few miles of brisk walking into your routine with a moderately heavy backpack and good posture (no/minimal slouching or l

I've found that simply incorporating a few miles of brisk walking into your routine with a moderately heavy backpack and good posture (no/minimal slouching or leaning forward) is reasonably effective exercise, particularly if it's at all hilly. I think it works out similarly to low-intensity deadlifting and squatting, and becomes much easier if you also lift consistently. As a bonus, it's also fun and relaxing.