Are you your best friend or worst enemy?

Have you got the willpower to say no to something you want because you know it’s not good for you in the long term? Your answer to this question will give you the answer to the original question.
However, nobody travels through life without being an enemy and a friend to themselves at some point during their journey. You’ll find the more mature a person becomes the more likely they are to be their friend. I would use age, but I’ve found that age is not a good indicator of maturity.