Yeah, I've got two boys, 6 and 2, and let me just say, boy are you in for it!
Did you know studies have shown that the vast majority of people cease to grow in any substantive way around the age or 25-30 and generally don't start up again until their 50s or 60s. Any guesses why?
Two recommendations. First, make sure that you schedule time for yourself to pursue your aspirations; also make sure your partner does the same. Two kids is exponentially more effort than one, so it's going to be that much more important to mutually ensure each other's sanity and fulfillment.
Second, realize that you're not going to be able to do everything that you want to do in terms of personal growth just because the needs of your kids will come first. But that does not have to be a limiting factor. If you're taking a growth approach to life, being a parent will give you opportunity to grow, though it's not a guarantee of growth.
And most importantly, have fun. Nothing promotes growth more than finding joy in everything simply as it is. No need to explain, rationalize or find a reason why bad is good; just live in joy all the time.