Same here, like the others, diagnosed at 24 while in the service, a long way from home. Thought my life was over, but luckily I was way wrong. I was on Asacol for quite a while. Like others have said, it's a pretty tame medication.
At 21 your life is just starting, and while Crohn's is not fun, there are a lot of really good medications and treatments out there that work. I work full time, I'm married, I have a 5 year old son, I travel, I camp, I mostly do what I want to. Of course there are times I get sick and need to take it easy, but I find ways to cope with that.
Hang in there, and be careful about what you read on the internet, there is a lot of scary stuff out there on this disease. Make sure you filter what you read, and talk with your doctors.
And, Hey, I'm 41 and I think I'm WAY to young for this crap!
My doctor told me to avoid the internet and if I have questions to talk to my GP or IBD nurse.