If you have put in all the dedicated hours of training that the plan you are following prescribes, and you have looked after your nutrition, and you have had regular sports massages to keep injuries at bay, who will come out on top when you're up against someone who is your equal physically and has done just as much training as you?
The victor will be the person who has the mental edge. The person who performs better when the pressure is on. The person who is better able to put into practice the strategies they have developed. The person who can embrace the pain and push through the suffering better. The person who can concentrate for longer at the key times so that their performance doesn't dip. The victor is the person who has prepared themselves mentally!
Is this person you? If not then there is a large area that you are missing out on, which seems such a shame when you have put in all the hours of hard physical training and gone to all that expense to get yourself physically ready. People buy the latest equipment thinking it will help them train better and race harder, but, you could spend less on those shiny toys, and invest that time (and money if you pay to see a psychologist) on training your brain to work for you rather than against you.
How we think affects how we feel which affects how we perform. If you think negatively ahead of the competition/race chances are you won't perform to your best potential. If you have been hitting good numbers in training but can't reproduce it when it matters have you asked yourself what role your head has to do with that?
Are your goals unrealistic so you're putting too much pressure on yourself? Is anxiety affecting your performance? Are you focusing on things outside your control and then haven't got a plan B when those things don't go as planned? Are you finding your training/race strategies go out the window when ego/adrenaline kicks in and you start to race against those around you rather than sticking to your plan, only to later crash and burn?
All these things make the difference between whether you perform to your potential or you again leave disappointed. Don't keep making the same mistakes. Things can change if you spend time on learning new ways of managing your mind so that it works for you rather than against you.
What makes or breaks your performance? Your mind!