When you become so determined that you want to feel good - you have become as your Inner Being is, in such a pure place of Positive Energy - then that which is 'negative energy' simply can't mix with you. It defies Law. If you are very strong and clear about your positive wanting, and feeling it, then 'bad' things simply cannot get in. Colds can't get in, car accidents can't get in, anything that you are not wanting cannot be your personal experience.
It's good to fail now and again - you learn a lot more out of failure than you do out of success.