hang in there Tetra. your Dad sounds like a sensible chap - we often cause ourselves pain by worrying about things we can't influence, but worrying about something that we might cause by worrying is even more self-defeating!
I'm not AA's greatest fan, but I do like the Serenity Prayer:
[God,] grant me the Serenity to accept the things I cannot change
the Courage to change the things I can
& the Wisdom to know the difference