More positive thoughts. No negativity": when Federer advised Fognini at the 2019 Laver Cup

During the 2019 Laver Cup, Roger Federer gave his advice to Fabio Fognini. Between accepting shots, staying positive, and setting good intentions, the Swiss showed that a player's strength lies as much in the mind as it does on the court.
Fabio Fognini, now retired, participated in the Laver Cup six years ago. The Italian, always flamboyant and expressive, was struggling in his singles match against Jack Sock, who had dropped beyond the 200th world ranking at the time.
Seeing his teammate getting frustrated quickly, Federer came to his aid:
"More positive thoughts. No negativity. If you step back on the return, do it with good intentions. If he hits a good forehand, accept it. If he was lucky, it doesn't matter.
You can't be frustrated and think that something bad is going to happen or that he was lucky. Make him hit great shots. Accept it if he does and just keep going over and over.