Hey Joe... no one is ever too old to workout, but you may have to watch out for a few more things than a younger person in order to avoid injury. Without knowing what your workout routine is (what exercises, how many sets, reps, how much weight, etc.) I would say that in order to gain wait, you simply need to eat more every day. Can you give us a bit more detail about your workouts? How many days per week, what exercises you do, etc.