Unless you are female. There really is such thing as a biological clock.

edit: Before I get downvoted, insert "... and want children"

Having children when you're young is a good idea primarily because kids are exhausting, and take up a LOT of time. Have them as young as you're able and wanting to do so: nothing to do with your gender. Men have fertility issues as they age also.

If you can make a resource by yourself, outsource- in this case, adopt.

It will make some of the exhaustion go away, since it seems to be due to diverging circadian rythms between a newborn and an adult.

A say 4 years old kid would logically be less exhausting to raise.

Also, if the kid is adopted, it also removes fertility issues concerns.

Strike 2 birds with 1 stone!

I wish I could agree but a) 4 years old are just as exhausting (the first year is actually the easiest in terms of time you have available) and b) adoption is increasingly more difficult. I have friends who just adopted a baby after 5 years of tests and checks and more checks.

Foster care is another option, it's easier to 'sign up' and you can get school-age kids, who need just as much help as an adopted kid.

Interesting - when does the exhaustion function reaches a maximum ? I thought it was the hardest in the first 4 years.

(regarding the difficulties of adoption, they could be compared to the outsourcing cost :-/ foster care is a great idea, but may not work for people who want to have "their" kids)

To put it simply: exhaustion becomes superseded, or exchanged in kind, by fun as kids gain more ability to communicate and comprehend the world around them. It's up to you as the parent to decide what is fun and what's not: an engaged parent is going find almost anything fun when their kids are involved and equally engaged, tantrums aside!

Everybody should get to choose what to make their life "about"; life is so varied, it's hard for me to take seriously any pronouncements about what a certain specific segment should be about.