The key to life is happiness. The key to happiness varies from person to person, but here are a few things that might just work for you...
1.) Do what they absolutely love. If you dread going into work each work each Monday and are constantly counting down to the weekend---do something about it. Quit your job. Actively look for a new one. Figure it out. Life is way too short to spend so much of your life doing something you don't enjoy.
2.) Don't put an emphasis on being "busy." Too many people think being busy means being successful, but it's quite the opposite. The man who works 25 hours a week for $100,000/year but has plenty of time to spend with loved ones and hobbies is significantly wealthier than the man who works 80 hours a week for $150,000/year.
3.) Budget your money and don't overspend on things like Target trips or grocery store visits. You don't need to be clipping coupons, but the smarter you are about your bank account balance, the easier it is to relax, enjoy life, and save intelligently for extravagant vacations, home remodeling, or that new Rolex you've been eying. Mint.com has some amazing free tools that make it easy for you to recognize where you're overspending.
4.) If you're commute is less than ideal, start listening to podcasts and/or audio books on your way to and from work. You'll start looking forward to your drives instead of dreading them.
5.) Avoid middle-of-the-road restaurants---the kind with $60-$100 bills for two---when going out to eat. They all kind of taste the same and there's nothing really special or memorable about them. Instead, go out to eat a little less, but go to the best of the best restaurants. The food, experience, and memories will be far greater.
6.) If you can afford it, invest in someone to clean your house every few weeks. A clean home is truly a happy home and your time is better spent doing something you love than cleaning a toilet on your hands and knees.
7.) Put a focus on nutrition and health. Tim Ferriss' tactics, outlined here, are an easy to follow routine that works wonders and still let's you eat pizza and ice cream on occasion. You'll feel amazing, look amazing, and be happier.
8.) Happy people aren't concerned with what others think of them. Do what you love, dress how you want, act like you do---just be confident about everything. When you start doing things for perception instead of yourself, you lose.
9.) Buy less, but buy quality. Instead of racking up a bunch of H&M clothes and IKEA furniture, opt to build collections slower but of a higher caliber. Not only will it look better, but the nicer something is---the better you'll take care of it.
10.) See everyone as equals. Don't judge, point out flaws, or be a negative person. Search for good, not a laugh.
11.) Find a solid tailor who won't charge you an arm and a leg. A few pieces of clothing that fit perfectly are worth more than a dozen pieces that just fit OK. Looking good = confidence. Confidence = happiness.
12.) Talk less, listen more.
13.) DON'T sleep more. Many people think they'd be so much happier if they only got ten hours of sleep each night, but the truth is, your body will be just fine with seven hours. Less time sleeping means more time doing things you love. Get out of bed and start living.
14.) Dream big, but with realistic stepping stones. Don't think your next great idea is going to make you a billionaire within 6 months, but don't be afraid to start something and slowly build a successful business over time.
15.) Never ever ever ever settle. Love, friendship, work, fun---expect the best from your self and your life.