This sounds like great advice to me.
It seems that so many people sweat the ‘small’ stuff, worries they can’t do anything about, yet they spend hours thinking about them.
If your problem has a solution then you can do something about it but why waste your precious time (and the time of those around you because it does affect them too). Let it go. Trust that everything will work out as planned.
Are you sweating the small stuff you can’t change?