Since I'm one of those older people considering a thru of the AT, need to get in better shape.

Haven't been in a 'gym' since my active duty days, just watch what I consume and hike/bike.
Since I carry this 'Tablet' thing everywhere or my 'smart' phone, I make them do a little work. (help me in weak moments.)
Seems the older we get, the easier it is to slide into some bad habits.
I find that the act of entering info or checking my progress on these 'things', helps me focus on my goals.
Guess I want to say, don't fear these 'tech' things. Make them work for you!

Some apps I use:

My fitness pal - My main calorie counter and goal setter.

Endomondo - Use this one to keep track of my hikes and bike outings. Very nice with the GPS thing.

Jefit - This one even has exercises for us old timers; like this one a lot.

Restaurant Nutrition - nice app for when you have to eat on the run. Let's you know the info on what's on the menu.

Hope these help some. Nothing you can't live without, just a different way of getting fit.