Thankfully, I am in excellent health for someone who will be 29yo in May. I have had a combination of early Dx and very good care and a bit of luck. I wonder though, how hard it will be when the health I do have fades.
It seems that when one enjoys good health ( or relative good health) the loss of that is much harder to bear. While it does probably suck to be rather sick at an early age, you at least have the benefit of not knowing any better. I guess one could compare it to being born into poverty, rather than falling into poverty late in life. Likely those of you on this site who were diagnosed later in life can attest to this.
Having said all that, I think most about losing the health I have and having to cut down on a lot of the activities I enjoy now, or drastically increase the amount of medications/treatments I do.