from Don't Let Me Be Lonely: “A father tells his son the thing he regrets most about his life...”
A father tells his son the thing he regrets most about his life is the amount of time he has spent worrying about it.
Worry 1. A dog’ s action of biting and shaking an animal so as to injure or kill it, spec., a hound’ s worrying of its quarry; an instance of this. 2. A state or feeling of mental unease or anxiety regarding or arising from one’ s cares or responsibilities, uncertainty about the future, fear of failure, etc.; anxious concern, anxiety. Also, an instance or cause of this.