Bob Hope (searchhad it right.

He used to joke that age was a state of mind, "that is, assuming you still have a mind." But it got me thinking: It's nice to live a long life, but it's nicer still to do something with that life and make a difference in life.

That's why, to me at least, it doesn't matter how long we're here, but what we do when we're still here.

A lot of people make a lot of difference not living a lot of years. I remember not too long ago a young man in my daughter's high school, dying of cancer. He was only 18 years old. But it was amazing how many lives -- young and old -- he had touched in that time. Friends who recalled his compassion. Nerds who remembered his understanding. Jocks and athletes who reflected on his sense of humor. He touched one and all and he was only 18.

It's cruel to go young, but it's nice to go loved.

Bob Hope was loved. This young man was loved. Each for touching others and each in his own way.

I remember one time talking to a doctor who worked with critical care multiple sclerosis patients who talked about his good and bad patients. The bad patients, he said, don't know how good they have it and the good ones, don't know how bad they have it. The difference, he would tell me, is the good ones smile through it.

Bob Hope smiled through a lot and was richly rewarded in years and laughter.

This young man my daughter knew smiled through a lot too. But was he richly rewarded? I think so. He made others laugh and others think.

That’s not a bad commentary on a life, whether it lasts 100 years, or only 18.

Watch Neil Cavuto's Common Sense weekdays at 4 p.m. ET on Your World with Cavuto. 

Neil Cavuto serves as senior vice president, anchor and managing editor for both FOX News Channel (FNC) and FOX Business Network (FBN). He is anchor of FNC's Your World with Cavuto - the number one rated cable news program for the 4 p.m. timeslot - as well as the FNC Saturday show Cavuto on Business. He also hosts Cavuto on FBN weeknights at 8 p.m. In addition to anchoring daily programs and breaking news specials on FNC and FBN, Cavuto oversees business news content for both networks and FNC's weekend business shows, including Bulls & Bears, Forbes on Fox, and Cashin' In. Click here for more on Neil Cavuto.