In older times, having children was not perceived as a burden but as a good in itself. Is motherhood a neutral event, which each age has positive or negative connotations? Of course not. Parenting, parenting, and childcare should be enjoyable in itself.
The behaviors that are essential for the survival of the individual or the species produce pleasure. Animals do not know that food contains nutrients necessary to live nor that sex is necessary to reproduce. They act motivated by pleasure. It is necessary to care for and feed children for years. No animal does it for as long as humans, so it is a complicated and lengthy process. We often bow down to the social norms of today without giving a second thought to our own mental health. Additionally, there appears to be an essential feedback mechanism that the more you care for a baby, the more you want to continue to care for it. You fall in love.