When I was just getting started I'd look at a map of the area and keep going a bit farther. Looking for roads I hadn't been on before. As time went on, this would take me onto longer rides every couple of weeks.

RidewithGPS.com is a great way to see your area and make routes. Easy to check the distance before you go. Also to see ways to shorten if required.

Take adequate hydration/nutrition on the bike once you get to rides that are going to be over an hour.

Think of it as an adventure!

Keep with it.