Agree with above, give yourself a a rest day or two between ride days until you are in better shape. Maybe stick with two days per week until you're comfortable. Make sure you are eating and drinking properly. Eat a proper breakfast and for an hour ride make sure to have a water bottle along. Plain water is fine but you can also mix in some Exceed or Secret Drink Mix if you want.

Is your bike seat the proper height?

DO NOT GIVE UP :-)