Sorry minimad but i have to disagree. You are confusing negativity with being realistic. Listen to what is being said.
As someone who was very enthusiastic and ever optimistic of any situation; life can teach you some very harsh lessons. Once you have your licence and start using it commercially it is a totally different ball game.
Yes you sound naive and I know many 21/22 year olds who are much more informed than you are so age isn't an excuse for giving dreadful advice.
Positivity is key but I guess you'll learn that there needs to be rational thought at the heart of every decision not boundless over excitement.