that's a great question, even asking "what would you do if you only had fifteen minutes per day" is an excellent question to give you momentum every day.
And definitely don't let the excuse of "I'm too young" or "I'm too old" or "I'm too busy" get in the way of what you know you need to do to make your dreams come true. I was just thinking about what Dr. Hardy said too and I was thinking about how old I would be 20 years from now. I would be in my 80s, but right now I am in my 60s and there's a lot that I can do in the next 20 years. I am not "too old"!