Strange Thing This Grief

I lost my father in November.  Strange thing, this grief... Where did it come from?  Where does it go?  It shows up out of the blue and then lays doormet for weeks.  I don't doubt my love for him or how much he meant to me... or even the fact that I miss him all the time.  But I do feel weird that I am not struck by constant numbing grief that binds me to the point of incapacity.  I feel guilty for not feeling that way, yet I feel sane for it.  I knew what type of man he was and how he would want us to behave.  Maybe that is what I move to.  Maybe knowing that he would want us to all continue to live successful lives and enjoy our time with our family and friends is what has me motivated to move forward every day.  Maybe the thought of staying still scares me more.  Strang thing this this grief.