Maybe it had something to do with the rest of Walter's friends? Maybe an accident?( because there is a dream on the first day I think? that is about where Walter got the pendant) and someone said " You better be up again"( i don't know if this is exactly what is said there) on the promise that they made.(It looks like Walter and that Friend of his made the promise in the hospital).
It's just a hunch of mine.....😊😊😁😁