Surviving Mid-20s

For every college/ university student, planning for the long summer vacation is always top on the agenda.

Filling all the gaps and dates with activities, internships and everything else seems to equate with having a life filled with good memories.

Ask anyone who is in their 20s to imagine their future, most probably they will think of career, marriage, family, investment and so on.
Probably anything but being seriously ill or death.

What if my life isn't long enough for me to build an established career, getting married, having children and everything else?
What if I don't have the chance?

My dearest cousin who is in his mid 20s has a brain tumor. He had it removed by a surgery a couple years ago.

But due to the surgery, he began to show abnormalities in his brain functioning; memory losses etc.

And because of that, he is gradually losing his ability to work and even the ability to drive. At his mid 20s.

His family could afford the best doctors in the city or the region. He has no financial worries.
But, I guess most of us trust modern medicine so much that we thought medicine and doctors can bring people back to their healthy state or even bringing people back to life, no matter what they suffer from

Not that work is of huge centrality to him, but losing the chance to be the best he could at this age, could he (or anyone) deal with it?

What am I supposed to say to him?
What would I feel if I were him?

He is just like a brother to me. I couldn't describe to you how heartbroken and sorry I feel for him.
I just want him to have a truly happy life filled with love and hope.

Love,
N