Work on your weaknesses
Some salespeople work on things they're good at and don't spend enough time trying to overcome weak areas. They can only improve their strengths so much.
Source: Mark Tewart, sales consultant
Even if they do improve strengths, there's a good chance no one will notice, since slight improvements are hard to spot. Strengths will take salespeople only as far as their weaknesses will allow. Be grateful for your strengths, but work on your weaknesses.
Try to do a "weakness" audit each week. What situations in selling make you uncomfortable? Where does your sales manager suggest improvements are needed? Write them down. When you improve your weaknesses, the difference will be dramatic and visible to everyone.