The Rabbis use an expression: זיקנה קפצה עליו to describe one who suddenly has old age overtake him. They say that there are four reasons why this happens with examples from Tanach.
David became old because of his fear of sin after the incident with Bat Sheva. So fears can cause instant old age.
Evil women led to Shlomo’s becoming old. It is written that old age came together with his heart being turned away by other women.
Aggravation from children was the cause for עלי הכהן. His son’s had sinned and brought on his old age.
And finally, wars were the cause of Yehoshua’s becoming old. It says that after all of his battles, Joshua became old.
So all we have to do to stay young is to avoid being consumed by fears, stay away from evil women, not get aggravated by our children, and not fight too many wars. Sounds easy enough!