...biological, adoptive, or anyone else who stepped up to the plate... never forget how fortunate you are. Think of everything you have now that would be lost without her in your past. Think of everything that would change if you lost her now. And don't forget to tell her how great she is.
And if you've already lost your mom, remember that you were most assuredly her everything, and remember all the priceless things she gave you while you had each other.
And even if you don't have a great mom... remember that you still have her to thank for life itself.