When you're honest with yourself about your weaknesses, and willing to put some effort into working on them, you identified a powerful pathway for self improvement.
Imagine a boat with a leak in the hull. Working on the engine might marginally improve its performance, but that really won't do much good because the boat will sink if the leak isn't fixed. A single weakness can sometimes outweigh all the strengths combined.
It's fun and easy to spend time doing the things you're good at. And you certainly want to take full advantage of your strongest skills. Yet usually you can only get marginally better at the things you're already skilled at doing, even with constant practice. However, when you set out to work on your weaknesses, the effort can produce dramatic, leveraged results. Identify your weaknesses, put some effort into them, and you can make a tremendous positive difference.