A really good post, and so positive!
I would agree with everything you posted here, with one exception - you CAN make people happy around you, while you are in the depths of misery yourself.
I talk from personal experience.
Making people happy around you IS the important thing, totally.
And sometimes that means not expressing your own internal negative situation, or circumstances.
'Grin and bear it' can be a must, at certain times. - to make people around you, happy