I'm particularly interested as an international who did my undergraduate degree in the US and is currently working in management consulting. Would be great to hear thoughts from Asians/Asian Americans who've gone through the process or from non-Asians who have a view of this issue and have experience to share.
Being bold and assertive, both in terms of communicating a vision as well as standing up for yourself, is something I've struggled with as an East Asian entrepreneur, and it's something I also see other Asians/Asian-Americans struggling with. Growing up, my parents always instilled a respect for hard work beyond all else. If I worked twice as hard as the competition, I'd achieve my goals. But what I realized as an adult is that your work ethic is just one part of a successful career. You need to know how to promote yourself and how to influence people, and these were areas that I was totally unprepared for. What was perceived as "lack of confidence" was really mostly shyness and a desire to keep my head down and plug away. You can lose out on a lot of opportunities with that kind of mentality.
What changed it for me was reaching out to non-Asian friends and peers who I admired and asking for their take on how to deal with a particular situation. How do I sell myself in this email? What kind of approach do I need to take with a prospective client that will allow me to close him or her? I'd then use their suggestions as close to verbatim as possible, and ignore the natural feeling in my gut that said, "Stop! This is not polite!" and push through. The results were undeniably better this way, which was encouraging, and over time, these new methods of communication and assertion started to become habitual.