One thing I've learned as the years have passed is I am 100% control of my happiness. Such a cliche thing to say, but it couldn't be more true. If I could've learned this as a angsty teenager I can only imagine how much that would've helped me through those years.
I have a million things I could complain about every day (exaggeration), but I have two million things to be excited and thankful for. Today for example, I could have complained about anything from not having enough time to get everything done before leaving town, feeling bloated, etc. but instead I'm choosing to be happy that I'm lucky enough to go out of town regularly and that I'm bloated from eating a little too much good food.
You may not be in complete control of your day, but you are in control of how you see it and feel it. Be happy, it's up to you.