Build the habit of eating healthily and exercising. Your body will thank you YEARS later.
Choose who you spend your time with carefully. You'll be the average of the 5 people you spend the most time with.
Understand that no one has it all figured out. Don't place unnecessary stress on yourself by believing that you should have everything set in stone.
Polish your communication skills, which will affect you for a lifetime.
Travel as much as you can. You'll never find it enough. If you have the opportunity to travel, seize it.
Don't be afraid to express your emotions. You never know when they might not be here to listen.
Take your work seriously, but not yourself. Your work is your contribution to society. Perform to the best of your abilities. You are a carbon-based life form, much like everyone else.