You listen to their woes and share their triumphs. You give them a ride or a few dollars. You wish them well on their birthday.

You tell them stories of your life. You entertain them with puns. Well, maybe they find the puns punishing, but you know what I mean.

Your pets depend on you too. They look forward to seeing you and sharing a loving existence with you. Without you, Rover and Fifi might have to find their own food. That could go seriously wrong.

Then there's your employer. Maybe you are not a dream employee, but you show up and do your work. Day after day. The replacement person might not function. Too much alcohol, too little conscientiousness.

Think of the other people in your social groups. Your dance group, your charity group, your religious-study group, your AA group. Your groups can go on without you, but your exact contribution cannot be replaced. There is no one quite like you.

Consider all the wee things that depend on you.

About 68 trillion living cells call your body home. About 38 trillion of those cells are bacteria that live in your digestive system or elsewhere. Usually, they help you and do not harm you.

Your body created about 30 trillion of the cells in you. For the most part, they cooperate beautifully with each other.

Want to find a miracle? You are it. A platypus is also a miracle, but that is a story for another time.

Many of the cells created by your body have mitochondria, tiny structures that provide the cell with energy to do its business.

Mitochondria almost certainly were once bacteria that merged with another organism billions of years ago. The happy marriage proved so mutually beneficial that the resulting creatures evolved into almost every known multicellular life form, including humans.

So, although you look human (I hope) in the mirror, you are actually a hodgepodge of life forms at the microscopic level. You have the face of a single individual, but deep down you are a corporation.

If you take your last breath, the whole corporation perishes. You have at least 68 trillion reasons to keep going.

If you ever ask yourself whether you matter, answer yes.

John Malouff is an Associate Professor at the School of Behavioural, Cognitive and Social Sciences, University of New England.