Thoughts and prayers are with you and the family of your friend.
My son, 18, and I both ride zx10r's, dirt bikes, rock crawlers, snowboard, and free rockclimbing. We love life and the adrenalin rush that comes with these activities. We have both discussed the possibility of one, or both, of us dying during an outing and have both promised each other that in the event of an accident we would honor the other's wish that we would continue on, secure in the knowledge that the deceased died doing what he loved.
Mourn the loss of your friend, then honor his memory by continuing to do the things that brought you and him joy. Ride on brother.