Alone among the creatures, as far as we know, human beings need meaning to survive. Added to air, food, water and reproduction, we humans need to know why we exist: the meaning (reflection on the past) and purpose (direction in the future) of our lives.
My belief, my religion, is that God gave humans 3 ways to create meaning: unconditional love, altruism, and giving one's life or dedicating one's life to something larger than ourselves.
Unconditional love I learned and received from my father. Sometimes he disagreed with my actions, but he never ceased loving me. It never would have crossed his mind. His unconditional acceptance of me gave me the freedom to become myself, to live into and choose my own destiny. It was a huge gift.
Altruism is giving something without hope of reward. Countless times I have had this discussion: "There is no such thing as altruism, because when you do something altruistic you feel good about it, and that's the reward!" If a soldier throws him/herself on a hand grenade to save her/his buddies, sacrificing life, their last thought may be satisfaction at saving comrades, but it's altruistic nonetheless. Humans gain meaning from doing for others without regard to self interest. You might not know it's the right thing to do if you did not feel the internal satisfaction that accompanies doing the right thing regardless benefit to self. But there's a world of difference in sacrificing for others versus gaining for yourself.
Finally, dedicating our lives to something larger than ourselves: an organization, a concept, even God. The greatest of these is God: to do what we understand God demands of us. In Judaism, that's the mitzvah system: to know clearly that our lives are purposeful because of God's intention. Liberal Jews have a greater problem with this than the Orthodox, but we, too know that God asks of us to be moral people (Justice, justice shall you pursue: Deuteronomy 16:20)
So much in our lives screams that materialism and sensuality provide meaning. Acquisition in all of its forms: of material possessions, of money, or another human being by conquest (think #metoo or just contemporary dating) destroys meaning rather than creating it. People so often pursue bankrupt goals, and then wonder why life seems empty. Pursuing an empty vessel, you are not going to end up with fullness of life!
Friendship can be a form of unconditional love. Disrupting life for another human being can be a form of altruism. Volunteering to reduce pain in others' lives can be a form or tying your life to a cause greater than yourself.
If you are feeling empty, you might want to consider these ideas, and ask whether you have received the wrong message about why you are alive. Now's the time for change, redirection, and the wealth of a meaningful and purposeful life.