This right here, is the greatest advice anyone can give you in life; well if you want to do something with your life that is. Preparing yourself is important sure, however it is of less importance than doing whatever it is you want to do. Aspire towards a goal and move towards it.
I have done this myself over the years and I am now starting to learn that I should have spent the last ten years of my life moving towards my goals rather than perfecting my crafts.
So whatever it is in life you want to achieve, every single day, take steps towards that goal. If you stray from that path, correct your course and continue forward. You will learn plenty on the journey.