Helping others is a basic tenet of many spiritual traditions. For example, Buddhists consider compassion for others as a basic spiritual development tool. And early Christians won many converts by placing a priority on helping the poor.
In AA "service work" that is, helping other alcoholics to get and stay sober, is part of the twelfth step. This goes back to the very founding of AA. Bill Wilson, just a few months sober and out of town on a business trip which had resulted in failure, had the realization that it was his work with other alcoholics that was keeping him sober. He immediately set out to find someone to help and eventually found Dr. Bob, and the program was launched.
It seems impossible to someone raised in our material culture that giving something away results in more rather than less. But the spiritual realm is beyond the material. The best solution is to try it. Try giving some thing or some time to someone who really needs it and you will find that you are rewarded beyond what you gave.