Terry Goodkind in each of his epic novels in the series, "The Sword of Truth", spends the time making a point guarded around one of the Wizard's Rules. In the book "Faith of the Fallen" he lists out the sixth rule:
"The only sovereign you can allow to rule you is reason."When you realize that there is nothing holding you back from doing anything that you want only then can you exercise full control of your life and not so whimsically outsource your sovereignty to some other feigned authority. There is no man in the sky, or some other supernatural control of events that are going to keep you down. Sometimes in life we experience things that are of no cause of our own but are just the choices of others being acted upon us. In other words a lot of bad things that happen to us is just plain bad luck, nothing more. Our solipsism would have us believe that there is something out to get us.
One of the most unhelpful pieces of advice that may be proposed is that your life is yours, live it. We can be like children in this universe. When a child finds something unknown to them, such as a stick or a rock, they don't try to think of the purpose that such things have, but instead make one for it. Many a childhoods summer has been passed by hitting rocks with sticks, is there less meaning in knowing that there is no real purpose for the rock nor the stick? Our life can be the same, so what if there is no divine purpose in it, make one. Make whatever you want of your life, live it as you see fit. You no longer have the obligation to subjugate yourself, oppress others, pay homage, suppress your thoughts, abide to any dietary restrictions, or restrict who you sleep with nor in which position.
Knowing all this should cause you to appreciate life all the more. Knowing that your life is but a blink in the timescale of the universe. Knowing that we are at an age where we can see into the past to the very beginning of the universe, something that may not be accomplished in the species of our posterity. Think of how much of a true wonder it all is, and knowing that after this there is nothing, how can you squander it on things of no worth. But even in this there is a fallacy, for what is of worth? It is given to each of us to decide this on our own.
Some would have you believe that if love has no meaning, if it is just a result of biological evolution, that somehow by being just a chemical reaction it is demeaned, unjustified, illogical, or fake. Love is still what drives our species and ensures its survival. Is a watch less marvelous once you understand its mechanics? Is thunder less thrilling knowing it is merely a reaction of an exploding atmosphere?
There are those who come down this path and become anti-theists, spending their time arguing with theists, Christopher Hitchens being among the most renowned of them. It is a good cause, helping others realize the truth, and if it is something that you love doing, then do feel free to do it also. Others just go about their lives, doing what they want, which in many respects would be exactly what the anti-theist is doing. There are also many communities online for support of atheists.
An atheist is not someone with no purpose, rather someone with limitless purposes at their choosing. You are the boss of your own life and are in a very unique time in our universe. Nothing is loss by an unbelief in deity or of the supernatural. Life is not just to be lived, but to be enjoyed.