I'm too young. I'm not old enough. I don't have the money. I don't have the time. I haven't been successful before. No one believes in me. No one will join me. I don't have enough information. It takes a lot of work. I know people who have tried and failed.
All of these excuses to not do something should be your reasons to do it.
If you've ever used any of these excuses to not do something that you actually wanted to do, give yourself the following self-analysis:
I _________ (your excuse) -- ok, well how long do you want that problem to persist? What are you doing right now that will change the circumstance? How long will it take you to get there without making a change? Are you ok with waiting that long?
You don't need motivation to overcome excuses -- the fact that you have excuses is the motivation.