Age matters. If you are old, forgetfulness occurs more often. Have you done a lot of drugs? They can fuck your brain, even weed. Everybody gets a mental block from time to time, but if it happens more frequently it is time to take it seriously. Not that there's much you can do about it, other than put your affairs in order. If your brain is going, it's going, and nothing can be done to stop it. Hope for a slow decline, and make sure someone close to you has power of attorney.