The most important thing is to believe in something

It doesn’t really matter whether you believe in one life or in many. The important thing is to believe in something, something that helps you live well, make progress, improve your life, and do good things for yourself and for others. Once again, if you believe in only one life, then you’re right. And if you believe in many lifetimes, you’re also right!
Both theories have value… as long as they help you improve yourself and attain happiness on earth.
Our most precious possession is the life we’re living right now. Whether you believe in one life or many, you can be sure of one thing: you’re alive in the present moment. The past is over, and the future hasn’t happened yet. The only thing that counts is the present. No matter what your convictions are, you should try to live your life as best you can, improving yourself, experiencing as much happiness as you can, helping others whenever possible and, of course, sheltering yourself from material need. And the best way to do that is to live as if this were the last life you have.
If you think you only live once, you should try to make this life a gem, a remarkable journey that leaves some kind of trace when you’re gone, not because you want to boast about your abilities, but because you want to set an example for future generations. Then, after your death, whatever is meant to happen will happen: nothingness, Paradise or Hell… you’ll find out, but only after you reach the other side.
If you believe in reincarnation, you should also try to make this life as positive as possible, because each new existence should be used to improve yourself. The positive changes you make now won’t have to be made again in your next life, as you gradually approach perfection. And the closer you get to perfection, the less often you’ll have to come back to earth to correct your errors.