Don’t worry too much about the past or the future. Live in the now. Right? That’s what they say.
Of course, Winston Churchill used to obsess over the future, imagining all possible scenarios and planning for them meticulously. He tried to know exactly what he would say in response to anything that a person could conceivably say to him. He committed it all to memory, as much as he could.
He became a great and widely-respected leader, speaker and thinker. It just goes to show that no advice applies equally to everyone, and common wisdom should always take a back seat to what works. Listen, try, experiment, apply reason, and use what works for you.