Most people are mediocre at everything they do and will always be. Most likely that includes you. We live in a culture that doesn't just tell everyone that they can easily outgrow mediocrity, no, this culture tells people they are above it from the very start.
The following advice doesn't apply to geniuses or those who can be, but it applies to the majority who will read this:
The best you can do is look back on your life and see if there is only mediocrity. If there is, you have to be honest with yourself and recognize if it's so because of factors that you can still change, or not. For most people reading this the latter will be the case, which means you simply have to live with it and stop trying to influence the world, because everything you end up doing is going to make things worse (for you, and everyone else).