If you've long been the sort to hop off the bike and walk it up the hill, you'll need a little mental prepping first!
Accept that riding uphill is more effort. Once you stop fighting it mentally, you can spend more time motivating your body and learning how to make the ride easier on mapquest directions.
Get excited about the challenge of making it to the top of the hill. This is something that you're quite capable of doing and proving it to yourself can be a lot of fun in between the agony!
Don't expect to go fast. That's unrealistic and likely to wear you out before you've hardly begun.
Understand the benefits to your body of cycling on hilly terrain. Hilly terrain builds your fitness levels up by helping your body learn to use oxygen more efficiently. Also, the process of climbing the hill on a bike uses different muscle groups as you shift about on the bike to maintain maximum power. The climb allows you to work hard, and the descent allows you to recover, providing a perfect exercise workout per each hill.