hard core runners maybe skinny but they have a whole host medical problems. Running is quite impactful on your feet and knees. Hiking however is much less damaging.

Physical activity in general is good for you. If your not doing much now, 30 minutes a couple times a week is a great way to get your heart pumping. If after time, you find your short hikes don't get your heart moving, then just start hiking up hills.

What you personally need to get healthy is a question probably best answered by a doctor, but if you got 30 minutes you could be doing a lot worse for yourself than a nice walk.