Give yourself time.Ignore those voices inside your head that keep telling you that you should be reacting in a certain way. While you're granting yourself some time to get used to the news, try not to let your ambiguity show. You don't have to wax ecstatic about the impending change in your status, but keep the fact that you are less than delighted under wraps.
Accept your lack of control.
For some grandparents -- you know who you are -- part of the problem is that you weren't in on the decision. Your life is about to be drastically altered, and you weren't even consulted. And that's just the beginning. A new person whom you are destined to love dearly is about to enter your life, but someone else is going to be making all the decisions about that little person. You may not be invited to the birth! Never fear. You'll manage to bond with your grandbaby, but the sooner you accept your lack of control, the easier your adjustment will be. Now influence is a different thing. You can definitely have a lot of influence.
Look at the positive side.
The fact that you are not in control means that you don't have to plan your life around this little person. It would be wise not to schedule any major commitments for the due date, for the christening or for baby's first birthday. Other than that, you should be fairly free, at least until the child is old enough to have dance recitals and soccer games. You can still take that round-the-world cruise. You can continue to train for your marathon. Keep living your own life as long as you want to. If there comes a time when you'd rather be hanging out with the grandchildren, you get to make that call, too.
Remind yourself that grandparenting is a beginning, not an end.
Most of us are still burdened with the image of grandparents as being mentally stodgy and physically decrepit. In today's society, these stereotypes no longer hold true. Observe celebrity grandparents, or your friends who are grandparents. Educate yourself about the people who are breaking every aging stereotype that's out there. Then go out and shatter a few yourself.
Think about what you can give to your grandchild.
You don't have to be a cookie-baking grandmother or a baseball-tossing grandpa. Find your own grandparenting style. Think about what you are uniquely able to share with a grandchild, whether it be the ability to identify all the birds in your area or a knack for rebuilding engines. Prepare to share your passions with your grandchildren. They will love you for it.