@Matias I’m not sure Matias, that’s a bit like the chicken and egg cycle....there is a correlation, but it’s impossible to prove definitively. I do think that those with a sunnier disposition attract other people to them as they are better company and make others feel happy. They also can usually charm people into believing in them and their ability to do something...for instance in job interviews. It can be called charisma in pronounced cases. They can persuade others by sheer dint of their personality, they are born salespeople, regardless of the product, because they are principally selling themselves. I think these people will always succeed in life because they are born with a genetic advantage...throw in good looks too and they will go through life earning more money than their less charismatic friends. I am obviously only referring to extreme examples, but in general terms it also applies, but to a lesser degree, that optimistic people do better in life. I should have inserted the word “sometimes” after can .....making it read as “can sometimes” train themselves etc. I do understand that it is not an easy thing to basically change the way you are wired.