This is one of the most profound messages that I have ever heard, and once this metaphor was contextualized the premise was crystal clear. Simply put, some of the people who are closest to you may not necessarily be advocates for your progress or supporters of your dreams.
Someone who is with you will always want to see you win, help you win, and enjoy the journey to achievement just because they love, and support you.
If the person beside you is not with you, then they are nothing more than a proverbial thorn in your side. An impediment that could prove fatal to your dreams. That is why it is important to take stock, and examine those who are in your circle every now and then, and ask yourself, if they're with you or just beside you.