This world is a better place today because of many noble men who gave back much more to the society than what they got.
If someone taught you to excel in your vocation, you should consider passing your expertise to many more as a gratitude to the one and many who made you. If you are part of a social organisation which helps you in networking, business and friendship then you also must serve the organisation by taking up the leadership position. If you got a scholarship for your study in a top university, you may consider taking responsibility of education for others.
Many of us never spent a penny on the roads we travelled. Many got treatment at government hospitals for free. Many studied at a fraction of cost at schools that were built on charity. One day, when we become capable, it may be a nice thing to share our wealth for the benefit of others.
If you are eating the fruits from a tree which someone else planted some day, you have a moral obligation to plant a tree which can bear a fruit for someone else, one day.
Remember, you must leave this world a better place than what you got. Remember, we just can’t eat the fruits. We must become the tree one day.