Negative thoughts increase stress and anxiety, which lead to poor performance. Positive thoughts on the other hand, do just the opposite. They help you relax and therefore increase performance.
Early in my marathon career, I was running a marathon with two friends who were faster than me. My plan was to stay with them for the first half, then slow down to my usual pace for the second half. When we crossed the halfway point, I was feeling really good.
Then a lightbulb turned on -- I realized I was actually talking myself out of running faster.
There was no reason to slow down. It turns out I was telling myself, "I'm not fast", and it was actually making me slow down. Getting rid of the negative thoughts about myself allowed me to run a personal best.
The first step is to identify negative thoughts and stop them before they start. If you think, "I can't do this" or "I'm not fast", you're probably not going to be successful. Everyone has these thoughts at one time or another. The trick is to keep your mind occupied with positive thoughts, so the negative thoughts can't even start.
Three strategies to help you stay positive during competition:
1) Have a mantra.
Think "The Little Engine That Could" and his mantra: "I think I can, I think I can". Choose a word or short phrase and repeat it over and over in your head. For example, "I am strong", "I feel good" or "I got this". I like to concentrate on my form, so I use a combination of "I feel good" and "I feel strong and relaxed".
2) Set multiple goals.
Many things can happen in a race and some you have no control over. Having multiple goals allows you to still be successful if things don't go as planned. You should have a best-case scenario, an intermediate goal and an ultimate goal.
For instance, your ultimate goal may be to finish your first marathon while your intermediate goal may be to finish in a certain time, and your best-case scenario may be to place in your age group. If it's 90 degrees on race day, your ultimate goal of finishing may be the best you can do on that day. You can stay positive by telling yourself "this is the longest I've ever run" and "I am going to finish".
3) Practice positive visualization.
Similar to daydreaming, see yourself successfully achieving your goal. If your goal is to finish your first marathon, picture yourself running strong mile by mile and crossing the finish line. Picture yourself proudly wearing your finisher's medal.
Every race can be a learning experience. Concentrate on what's going right instead of what's going wrong. How you handle adversity is often the difference between success and failure.