Try to get out and climb someting once a week, get your legs strong and you will be able to move up progressively to longer and higher goals. Make goals to climb a certain amount of elevation in a hike: Consider thousands of feet of elevation your friend. It will make you stronger. Pick a mountain and tell yourself YOU WILL get to the top. Train yourself to rest as little as possible. If you take a rest, make it short--like 30 seconds, and keep moving.
You probably already know this:
Don't wear any cotton. No cotton socks, No cotton shirts, no jeans.
Carry water wherever you go.
I consider every peak and mountain around hear a worthy goal. I have a list of classics I like to do every year: Lone Peak. Pfeifferhorn, Broad's Twins, Olympus, Raymond. Also, the peaks up above Brighton are easy and safe: Pioneer, Sunset, Millicent, Wolverine.