You are your best and your worst advert simply because you are at the centre of your circle, and that circle is called your circle of influence.
Influence is the capacity or ability to have an effect on the character, development, or behaviour of someone or something.

Think about this for a minute, as human beings we tend to learn by stealth, or by mirroring or copying behaviour, which means that we permanently broadcast influential signals in all of our interactions.
If we start at home, make our way to work, extend this to friendships and other social interactions, you can see that your circle of influence is already very wide, the question is who are you influencing and what are you influencing them to do or become?

It was Jim Rohn that said “You become the average of the 5 people you hang around most”. That is a statement of the power of influence.
Proverbs 13:20 says Whoever walks with the wise becomes wise, but the companion of fools will suffer harm.
So what can you do to widen your circle of influence?
First there is a big difference between focusing on your circle of worry as opposed to your influence circle.
It literally is the gap between problem focused and solution focused.

You cant control, the weather, life circumstances, or the economy, but you can control yourself.
Proactive people focus on things they can do something about: health, learning, relationships both at home, and work. 
Being proactive is being responsible for where your life is headed, and in times of great pressure don’t get bitter, the idea is to get better and master your circle.