I think you're underestimating yourself.

I can control my own actions, so my worry about heart disease can inform my dietary choices.

We can control gun violence by influencing culture or changing laws, so gun control is an appropriate subject of worry.

We cannot control the sun going supernova. We shouldn't worry about that.

Good point. Judging from history though, law has been quite unsuccessful at preventing the problem of murder.

This is undoubtedly true on an individual level, but not necessarily true on a societal level.

(i.e. Things I can't control as an individual, we as a society might still be able to control or influence.)