Some ideas (in no particular order):<p>1. Start lifting weights and training Brazilian jiu-jitsu.<p>2. Join a Toastmasters chapter and start doing as many public talks as you can.<p>3. Go to all the various events you can, that involve mingling and talking with people... yes, it will be painful at first, but condition yourself to get used to it. Go to the various "mixers" put on by the local Chamber of Commerce, and similar events. Or just all kind of Meetups that might interest you.<p>4. Hang out with other sales people and model their behavior.<p>5. It's maybe a bit extreme, but you could try "rejection therapy".[1]<p>6. It's a bit "out there", but honestly, one of the things that did wonders for my self-confidence and assertiveness was the time I spent as a volunteer firefighter. When you put yourself in an environment where you routinely deal with literal "life and death" situations, it's hard not to develop a more stoic / detached mindset, and to learn a "feel the fear and do it anyway" approach.<p>7. On a related note, there are a bunch of books on this topic, including one titled "Feel The Fear, And Do It Anyway" (by Susan Jeffers). I have it, skimmed a little bit of it, but never actually read it. It came highly recommended though, so it might be worth a look.<p>8. It's become a bit of a fad lately, which makes me hesitant to mention it, but the Stoic philosophy has some appeal that might be relevant to you. Reading some classic, or contemporary, works on Stoicism might be worthwhile.<p>9. Read and study as much material on sales techniques / strategy as you can. I have found that in some contexts (like my firefighting days) confidence derives directly from training and the associated knowledge. Crawling inside a burning house is scary, but it's less scary when you know how your protective equipment works, when you understand how to recognize potential signs of an imminent flashover, when you know you can always follow the hoseline back out if you get lost, etc., etc. Know your techniques and tactics extremely well, and you should find it easier to be more confident.<p>[1]: <a href="https://en.wikipedia.org/wiki/Rejection_Therapy" rel="nofollow">https://en.wikipedia.org/wiki/Rejection_Therapy</a>