Want to be truly happy? Start each day with a positive attitude.
It's so easy to wake up in the morning and find everything that is going wrong. Maybe the pair of pants you planned on wearing have a stain, the shirt you wanted to wear wasn't washed, it snowed while you were asleep, you're having a bad hair day, the girl in the silver car cut you off, etc. etc. etc. You can find things that make you mad and possibly let them ruin your day, but why do that?
It'd be so much nicer waking up, making a warm cup of coffee, looking at the glistening white snow, and finding a warm & cozy outfit since the other one isn't clean. By ruining your morning with all the bad things, you inhibit yourself from being able to enjoy what the day holds.
I get it, sometimes there are just bad days, but don't fool yourself. You, yourself, no one else, are in control of your day and your mood. So have a positive outlook on things, I can promise it'll be worth it. You will be presented with more opportunities and you'll be more likely to say yes to these possibilities. People will want to be around you more, because let's be honest, no one wants to be around a grouch.
It may take a little effort at first, but give it a try. Typically the good things in life don't come easy. Be thankful and celebrate little things and then the bigger things will be that much greater.
