Remember this the next time you make a mistake (because everyone does) or the next time you're worried about something you have no control over. Let life happen! Every single event that occurs in your life is doing so for a reason. Live NOW, and enjoy!
Every decision you make now will affect your long term goals, even something as small as what you decide to have for breakfast in the morning can set you.
Practice gratitude - Every day is a gift and should be treated as such. Enjoy your days, enjoy the company of loved ones and of course enjoy yourself. You will never get back today, so enjoy every single second!
Realise that you are human, you make mistakes, and most of all, that you cannot change the past. Instead, look ahead to the future, knowing that you have the knowledge and experience to avoid making this same misjudgment. You can now make decisions with this new knowledge in mind - and in reality, your mistakes have helped you grow into the person you are today.