One very powerful technique that a hypnotherapist might use with Joan is also one of the simplest.  Once in a trance, Joan would be guided into a of series memories in which she played her best tennis, reliving the memories with hypnotically enhanced vividness.  She would be instructed to unconsciously connect the internal resources to some cue that would always be present on the tennis court, like seeing the net, so that she automatically steps into the most effective focused mind set for tennis, in the same way that she automatically reaccesses her ability to drive when she sits down behind the wheel of her car. 

Although a similar method might be enough to put Ted, the triathlete who buckled under pressure, in the winner's circle, it's quite possible that a different approach might be necessary.  Ted may have unconsciously learned at some point to believe that he "wasn't good enough" to be a winner.  Or, he may have developed a habit of telling himself that  he couldn't take the pressure.  A highly qualified hypnotherapist would help Ted resolve those issues, and help him build an unshakable resolve and determination that increases as competition get more intense.  The mark of good hypnotherapy would be that Ted would just feel and act differently in competition without any conscious effort to maintain the new beliefs, feelings, and behaviors.

Finally, there's Gertrude's desire to lose 23 pounds.  A hypnotherapist would consider whether Gertrude was simply eating too much nutritious food, making poor food choices, eating without hunger, or needing to resolve fears about being thin.   Surprisingly, one of the easiest things to do is to change a food preference.  It can be as simple as recoding the mind's internal representation of chocolate (yumm!) To that of white rice (ho hum).   After doing that Gertrude would lack any particular to indulge in chocolate.  It's obvious how that makes dieting a lot easier, especially since it's possible to do the opposite and make low calorie foods like salads and vegetables a lot more attractive (yumm!) Than before.

Since the mind and body are so intimately intermingled, it is also possible to use hypnotherapy to increase Gertrude's metabolism.   The amounts of energy burned literally increases, so that fat is consumed at a greater than normal rate.  That's obviously  to Gertrude's advantage.

Of course, as with Ted and Joan, the hypnotherapist would make sure that Gertrude built and maintained a great attitude to support the new lifestyle that comes with permanent weight loss.  That includes the sustained motivation to keep physically active and exercise regularly.