Sit back and stop whatever it is that you're doing.

The first step to this process is to do this: stop.

Simply stop. Think about what it was that you were doing.

Were you thinking about the problem in your mind? Was it pestering you to the point of annoyance? Did you let it ruin your entire day, or at least the past ten minutes of it? That's the time you're not going to get back, but in order to learn this, you're going to have to accept it. In order to continue, you cannot be doing anything else but focusing on the task at hand. Whatever it is you're worried about, it can wait. This time is for you.

Acknowledge what was pestering you and think, "Will this be important in five minutes? Five hours? Five days? Five weeks? Five months? Five years?"  

Next, you must process whatever it is you're thinking about. Sometimes our mind likes to spit information at us all at once, and this can be overwhelming. Pick it apart piece by piece-- write it down on a piece of paper if you have to. Think about it, but not in the way you were overthinking about it previously. Get right down to its bare bones; the core. Look at the problem right in the face. Then, ask yourself if the problem will be important within five years or so. If the answer is no, then it's not worth putting any more thought into. If the answer is no, then this problem is none of importance, it is insignificant in the grand scheme of things. This means that you are ready to proceed to the next step.

Take the biggest deep breath in, then exhale.

All of the gears grinding in your brain may be exhausting, so this calls for de-cluttering your mind. Inhale like you're about to scuba dive into the ocean for a long period of time, then exhale for an equal amount of time. This is to cleanse yourself and release the buildup that was caused in the previous task. Observe how you feel compared to before you let go of that breath. Do you feel any different? Is it like a renewal? Like you hit the refresh button on a computer browser? If so, let's continue.

Be glad that you overcame it.

Sometimes we will do something without rewarding ourselves. Pat yourself on the back. Bringing issues to the forefront isn't something that is enjoyable to most. Let yourself be happy that you summed up the courage to do so. It's one thing to complain about a predicament, but another to resolve it internally. It takes true maturity and strength to make inner peace with yourself.

Move on, and never look back.

In order to succeed in letting go, you must not bring it up in a negative light. If you find yourself thinking about it again, try to put a positive spin on it. Do what you love, and surround yourself with those you love. That will clear your head of the anxieties and/or that you previously were experiencing. The best thing you can do is start off this new chapter on a good note.