You can do it!!!! I've had a break of 40 yrs or so, and I found it difficult at first. I had a sore bottom for a while, but some padded shorts helped a lot. I decided I had to get some more exercise because I've had type 2 diabetes for several years now. I thought it was about time I did more than control my diet. You'll build up your stamina pretty quickly. I nearly fainted on my first ride. I've devised a little circuit for myself. I got a Garmin Edge 200 Cycling computer to add a bit of spice to my rides. It tracks and
records you by GPS, so you can do a circuit and try and go quicker next time. It also has a calories burned estimator, so you can go to the Fish & Chip shop afterwards.
Anyway, good luck, and stick at it.