I exercise eery morning. I used to walk 4+ miles a day (evenings). But ordinary walking on level ground does not do much for the quads (upper leg muscles).
These days, I do the tough version of Bulgarian (1-leg) squats before breakfast. On some days -- but not every day -- I feel the need for a short walk on top of that.
I get much more out of that short workout. Some of the payoffs include: an immediate psychological boost, slightly DECREASED appetite, and (obviously) stronger uphill hiking stamina.
I've written a few hubs about exercise for non-athletes. Check them out if you think that you have the right stuff to be an exercise wimp.