Since DD died just over a year ago I have found that "doing" is the best approach for me. Keeping busy doing things, either connected to the dead person's life in some way or not, has served me best. I think it is the distraction factor that I have found most useful, particularly learning new skills, both practical ones and mental ones. I guess my approach has been, and continues to be, to take on things that challenge me.
I believe DD's partner has used the same approach.
It is not total distraction of course but having to concentrate on things has definitely been helpful. I suppose, at a stretch, one could call it occupational therapy though I hadn't thought of it that way until just now.
As my mother-in-law said when her son, my b-i-l, died at a similar age to DD: "You just have to get on with it." She is still alive. It cannot be very common nowadays to lose both a child and a grandchild, especially considering they were both very healthy people up until their final illness.