" I bought a helmet and some gloves and a seat bag and tubes and tools and repair stuff, and I went to a class so I could learn how to do simple cycle maintenance and fix a flat."
SMART!

"I'm sad to say that one 2.5 mile loop completely wears me out and makes my legs really sore."
You don't want to get REALLY sore! Go easy at first. It'll surprise you how fast your legs will get in shape. Just don't make them angry!