I was asked the other day what I think about when I run. In all honesty, all I think about is the next mile. I'm in the moment, and my mind empties of all the insecurities and nonsense stopping me from thinking straight. I say that... the other day (when I was running) I did find my mind wonder. I was thinking, why, after all the runs I've done, hasn't running got any easier? You kind of think that one day you'll be able to run without getting tired or out of breath, but then a thought hit me.
I made the link between grief and running. In my experience, running doesn't get any easier, but my tolerance towards it has definitely increased over time. I feel that grief acts in a similar way, and you some how learn to tolerate it. The other similarity is that you have to set your own pace for both. If you increase to a pace you're not comfortable with, chances are, you're going to burn out. Stick to your own pace, and don't let anyone else dictate that for you. Grief isn't a sprint, it's a marathon.