Ah yes, fake it till you make it. That can work in certain situations, however my feeling is that its best to be genuine. That said learning to be better at communication and engaged with others takes practice so going in with the perspective of let’s see what works could be a less stressful approach then needing to be perfect every time. (A curse of being an introvert is a tendency to need to be perfect and not to “embarrass” ourselves.) Your written communication is very strong as is your engagement in your post, so you have a lot to work with.

I always hated the ‘speak up more in meetings’ comment on my reviews. I have learned to speak up in a meeting when I have something to say but for the most part I play the role of active listener. Making eye contact every now and then with who ever is speaking, leaning towards them (not in a creepy way) and nodding and smiling when appropriate. In this way I remain engaged even when quite. Funny side affect, it has been pointed out to me that often in a meeting people will be “talking” to me.  To be candid I’m hard of hearing so I have to be a active listener but my managers don’t need to know that. ?

You have additional challenge if your dealing with customers. Again, being an active listener can help with engagement. This is not about faking it but being genuine… assuming you care about your customers, which I bet you do. Such interactions are a great place to practice compassion while maintaining one’s personal boundaries. As an introvert you likely have developed a natural empathy and its ok to let that show.