Smoking, drinking and gambling never ends well. Stay away from addictions.
Don’t try to proof how manly you are to your friends/girls. It rarely pays off. Its ok to have a veggie dish at the restaurant instead of a bloody steak. Its ok to not speed with your car to look cool. Its ok to wear whatever the fuck you want as long as you like it, it fits well and its practical for you. Do what you like and be proud of it.
Always save time for your hobbies. Growing up doesn’t means you can’t have fun. If you are in a relationship make sure your partner gives you enough space and time for yourself.