Welcome to cycling, just got back from a 30 mile ride and my left foot is a bit numb from the clipless pedal, my right knee is sending signals for ice, my hamstrings need a good stretch, and I feel great, wanted to go farther but family obligations called, plan is to do about 50 miles tomorrow. You have joined that group of folks to feed the beast (the right amount of pain can be nature's way of telling you, you are working hard, learn where the balancing line is)