Maybe the answer is: Do something great with your life.
When you make a difference, you do something great. Even just take a little step. However small, the difference you make is proof the world needs you. When you help, when you have passion: You do great things.
The greatest honor to Robert, is to remember him when you are at your best. Just as the baseball player points to the sky when he hits a home run, there can be no greater honor to Robert and your friendship than to remember Robert fondly when you are at the top of your game. That's the message to Robert's loved ones, "Have a wonderful life, and while you are at it, THANK You for remembering him too in your happiness." Robert is like the patron saint of Joy (not Pity). I'm sure he will be happy when you are.