But working on your strengths takes you from good to great. You go from a good Excel user to an Excel guru. You even begin to monetize that strength of yours. People will only pay you for what you are great at, not what you are below average at, regardless of the amount of efforts it cost you. And that is why I think everyone should focus on their strengths.
Focusing on your strengths not just make you great at something, it also makes you feel good about yourself. It helps you to live a motivated life, knowing there is a value you can create better than most other people. You feel confident about yourself and that confidence radiates on your face and in your gestures, as against when you put all your energy into trying to fix your weaknesses and only achieving average results.
And to ensure that you are convinced, take a look at all the people we consider as legends: Michael Jordan, Michael Jackson, Usain Bolt, Lionel Messi and Tiger Woods. None of them became a legend at something they sucked at and later improved on. They all became legends at things they had a natural edge in and focused on them. Usain Bolt has always been an amazing runner; he, then, built a professional career out of running. Messi didn't become a goal wiz recently, he has always been a goal wiz since age 8. That was what got Barcelona interested in him at age 12. And I don't need to talk about Michael Jackson; he was born singing.
If you are serious about becoming someone phenomenal in life then you have to pay less attention to your weaknesses and pour out yourself on your strengths. Whatever you are good at, become great at it. In anything you do that make your ordinary efforts look extraordinary, it's time you became outstanding at them. Focus on your strengths.