Watch what you say. Forget the saying "sticks and stones may break my bones, but words will never hurt me." That statement is false. Words have unlimited power. People who fight get it over with but words can stick with you for life. Eliminate words like "I can't" and "impossible" out of your vocabulary. Using phrases like those will stop you from searching for solutions to your problems. Instead, replace those feelings of doubt with questions such as "how can I" and "what do I need to do to make this possible".
Pay someone a sincere compliment at least once a day, chances are your compliment will make their day a bit brighter, and they will pass that sunshine along to others.