I have nothing against children at all, I just never saw myself with a baby/child. I may well regret this in old age when I don't have adult children around me but I couldn't enter into a life I didn't really want just to prevent a possible lonely old age. DH feels the same way.
Unlike some of the other childfree people on here, I do regularly read the parent/child related threads just out of a sort of fascination with a life I will never live. Some of it sounds lovely - movie nights snuggled up on the sofa, Christmas Eve boxes, being greeted in the morning by a cute smiley little bundle looking for a cuddle, fun birthdays and Christmasses etc.
Some of it, and I know these are only small parts of a child's life, sounds dire - sleepless nights, exploding nappies, potty training, trying to get children to eat when they don't want to, the school run, worrying about their physical and mental health, the expense and difficulties of childcare, being restricted as to when you can go on holiday, having to put their needs first etc etc.
Overall, I would say I am very happy with my decision and DH and I have a lovely life. We have just paid off the mortgage so will make sure to make provision for any healthcare needs, as much as we can, for old age.