You can't fight emotion with reason; you need an emotional frame for your work. If possible/appropriate, tell other people what is going on with you, and ask them to hold you responsible (they will appreciate your asking and be more inclined to nag you in a friendly and understanding way). And try to think of how work is meaningful in your new life developments. For example, if you were expecting a baby, you would want to think of yourself as a provider.

Good luck and congratulations!