A Universal Appeal
I have found that people who have, and radiate Gratitude, have universal attractiveness and appeal. Some think that confidence is appealing, and it is, to some extent, but, it is not seen as universally appealing by most people.
When looking at this in the opposite way, it is clear that people who who complain a lot, and are angry and bitter, are definitely not seen as attractive or appealing.
Why Should We Care?
If my purpose in life is to be of service, being appealing to others, is critical to having others open up to me, to allow me to be of service to them.
How To Have Gratitude
It appears to me that Gratitude is a decision. It requires a force of will. When I have a hard time with this, I need to simply stop resisting Gratitude. When I look at this in the opposite way, I see that lack of Humility, having expectations, and general immaturity are the things that block me from feeling Grateful.