I've seen a pattern in my many years of life that I am really starting to utilize with my kids lately.
Kind of randomly, I was playing the Topgun guitar anthem in the passenger side with spotify in our minivan and then turned around in my seat to see my kids in their car seats. I started air guitaring and switching between high-fiving them and being over-the-top silly happy saying "ya ma, we are so cool..." etc.
The typical car ride is my wife driving my kids to school and me programming on my laptop with the occasional boring tone of me asking the kids about their school life. This day was totally different.
My kids were all grinning and excited along with me, seeming to be genuinely enthusiastic and joyous even though it was about nothing. After my little stunt I felt this happy glow inside that kept on the entire day. All my interactions with people were more fun and personal because I was more engaging and excited about life. It was like getting a charisma boost.
It then dawned on me that we can manufacture joy at will for no particular reason simply by acting it out, even sarcastically and in a silly way. Our endorphines just kick in the more you get into it. This phenomenon is even more powerful in groups. Sports teams, church, seminars, clubs, spectator events, etc. all have this advantage of generating pointless enthusiasm. I am definitely what you call a skeptic all about science and generally pragmatic. However, now I can honestly say that being enthusiastic in itself is all that really matters. The positive feelings that radiate out from you onto others has a deeper biological effect that connects with people immedietely.
Charisma is basically that and now I can freely summon it and feel inner happiness as an awesome side effect for no particular reason at all.