Good work getting on your bike. Lots of good advice above me.
Just keep riding. At least a couple times a week. Don't overdo it, just go a little further and/or faster each time. You'll soon build up to riding. Hopefully, you'll then be having lots of fun and not wanting to stop. It helps to get in good enough shape to join with group rides, so you can combine your exercise with your hanging out with friends time. Plus, saying you'll meet folks for a ride is a good way to prevent yourself from backing out of a planned ride.
If you're not careful, you'll start hanging out with other cyclists all the time, your wife will roll her eyes at all the cycling talk you do, you'll be spending huge amounts of cash on bikes and bike parts, you'll give up smoking so you can ride better (more than one friend has done this after getting fed up with always being the slowest - it makes a huge difference), you'll meet 60-year-old guys who are faster and better than you that inspire you to stay fit for life, etc., etc.
Definitely stay hydrated. Drink before you're thirsty. And bring a snack. If you bonk and you've got nothing to eat, it's really unpleasant to try to get home.