I find the idea of hiking interesting and really attractive in a general – yet at this point mostly theoretical – sense. Being outdoors (as opposed to merely outside*) is very appealing to me. However, where I live it’s difficult to find a route, trail, etc., that rises above merely “a walk”, though. With my interest in landscape photography, it’s a natural fit. Even carrying a ~18 lb. photo backpack could be construed as beneficial in exercise terms. 
But I think a hike should have an objective – a destination as it were, even if it’s a loop. There should be a reason for the hike, beyond just the exercise. That’s really difficult to find around here.
But I need to.
I turn 65 in 10 days. In a general sense I’m in good health: I take meds only for cholesterol and hypertension. Both are well controlled. Officially (per my medical records) I have a couple of other conditions but they’re mostly typical age-related things that don’t really impact daily “outward” life. Yes, I could shed a few pounds, but I’m more that 6 feet tall so I can legitimately carry a little bit. …a little bit. 
Mostly I’m just not fit in a cardio-pulmonary sense. Several years ago when I rode my bike on a semi-regular basis (i.e., once or twice weekly) I could do 25-40 mile rides. But I was always the slow one in the group, waaaay behind. I ran out of steam before anyone else – Not so much in muscular terms** but in my lungs. And I get temporary tachycardia: My HR goes up but once I stop exerting myself, it drops quickly back down. As a result strenuous activity is done in “spurts”: Exert, rest, exert, rest. And that pretty much precludes any group activities, since I don’t want to hold up a group. I’d rather forfeit my activity than impact someone else.
* “Outdoors” == Hiking, camping, etc.; “Outside” == Mowing / yard work, being at home, etc.
** To be fair, I’m a flat-land rider and don’t do hills very well at all. At. All.