I’ve sometimes wondered whether my bout with hepatitis C affected my lifespan. Probably not, according to a book I just read.

The Telomere Effect, by Dr. Elizabeth Blackburn and Dr. Elissa Epel, explains that, in general, the length of a person’s telomeres has more influence on their lifespan than all other factors, including diseases they have had.

Blackburn, a Nobel Prize winner, describes telomeres as something like aglets, the end caps on shoelaces. The plastic caps keep shoelaces from unraveling, and when the aglets wear out, the laces unravel.

Telemeres cap the end of chromosomes. Over the years a person’s telomeres shorten. When they become too short as a person grows old, cell division that is directed by the chromosome stops. Ill effects, such as the generation of cancer cells, become more likely.

A study in the World Journal of Gastroenterology suggests that telomere shortening is related to whether a person with hepatitis C will develop cirrhosis.

The study, by Lucia Carulli Ph.D., explains that when the liver is injured and trying to repair itself, “there is a high cell turnover.”

With each turnover, according to Blackburn, the telomeres shorten. Therefore, a lot of repair may equal a lessened ability for further repair.

However, states the Telomere Effect, you can protect your telomeres through lifestyle changes. Epel, co-author and health psychologist, suggests that people should change their response to stress.

We can’t prevent all stress our lives. Instead, Epel says, we should avoid panic or depression when confronting stress. Seeing stress as a challenge makes one—and one’s telomeres—healthier.