One of the keys to happiness is this simple: taking control of your life and your path in life, to the best of your abilities. Know that you have power over your own life, and know that you can control what happens in your life. With this, you must also know that you can’t control others; you can only control yourself and how you react to situations.
If you’re not happy, figure out why. Figure out some small ways to change that, even if it’s something as simple as getting a haircut to make you feel better about your appearance, working out more often to blow off steam, or taking up a hobby like painting or writing. Not happy at your job? Look for a new one. Not happy in your relationship? You can’t control the other person, but you can control yourself. Either decide to make an effort to fix things, or decide to walk away.
In fact, adapt that attitude in all aspects of your life. If something is making you unhappy — or not making you happy — figure out why, and either decide to do what you can to change that, or walk away from it. Don’t let things hold you down in life.
Recognize your boundaries, and recognize what you can and cannot control. You can’t control other people or how they may act towards you, but you can control how you react to them. You can’t control whether or not you get the job, but you can control how you appear in an interview and how your resume and application materials look to the manager. You can’t control the traffic lights or the line at the coffee shop, but you can control what time you leave the house in the morning.
Life is all about having control over your life, and your life only. Once you start to adopt that style of thinking, you may find that you end up a lot happier.