Think not of what you did yesterday, but what you can do for yourself today.
Having a great golf swing helps under pressure, but golf is a game about scoring. It's like an artist who can get a two-inch brush at Wal-Mart for 20 cents or a fine camel-hair brush from an art store for 20 dollars. The brush doesn't matter - how the finished painting looks is what matters.
Dennis Murray is a wonderful Golf Professional who is personable and skillful as an instructor. Dennis helped me work on my golf swing for a full week back in the 80's when I was still playing the PGA Tour. His instruction was great and helped my game very much.