This is really good advice and I agree in general with most of it.
For instance I do worry too much, however, I believe that in some instances it's important to worry and NOT be happy, or things will get worse, a lot worse, like a nuclear war...
Can I control the outcome?
No, but I can do my part and hope that others will do theirs, and then whatever happens at least I did my best.
As for liking everyone, as a Christian one is supposed to love everyone, even one's enemy, which means you have to even care for those who don't like you. But to be honest I find that really hard.
But caring about them doesn't mean you have to agree with them or being dishonest just to please them.