Oh the cliches ... but for me I think that being a mother has been the hardest thing I have had to do but also the most rewarding I have experienced so far.
Maybe I am corny and gave you ammo for the soapbox for yet another sappy description of motherhood, but I will take it happily b/c I stand behind my claims.
I have no problem with people saying that, for themselves, parenting is the most rewarding thing they have done. I have problems when the cliche is spoken in such a way as to suggest that people who do no have children are missing out on the potential for "the most rewarding thing ever," or when it suggests that there is something wrong with someone who is not having a rewarding parenting experience, or even that other things cannot possibly be more rewarding to themselves or others.
I have had a completely different career path than you so I have a different perspective. In my jobs and volunteer work I have helped the poor, the homeless, parents whose kids have died, women with HIV, and people with serious mental illness and their families. When I helped someone whom society has shunned, I have to say it was pretty darn rewarding. I wouldn't say that those things were necessarily more rewarding than parenting, but I did not find parenting to be markedly more rewarding than other things I have done. That's me.
Again my problem is not that people find parenting rewarding, only when that cliche is generalized to others. I never got a sense that you were overgeneralizing. And I like that you say "so far" because it leaves the door open for an even more amazing experience!
