Here’s an intersting inquiry from a runner with 10 years running experience and 4 marathons (improved on each).
I have problems finishing races. I tend to give up and walk a lot in the last few miles, no matter what distance of a race that I am doing?! I am always trained, but I think that my mind won’t allow me to finish well.
Well since it happens in all your races there are several possibilities. Without a complete background it might be hard to pinpoint.
One – your training may not be tailored to the distances you want to race – you cannot train the same for a half marathon and run a 5k fast. So even a marathoner trying to blast a 5k unprepared for that pace – will succumb to great fatigue. It is possible to be completely out of gas and need to slow to a jog or give in and walk. Merely because you are “trained” doesn’t mean you have properly prepared for a given race. Of course, each race can have unique reasons for slowing to a walk – most certainly in the marathons it’s an endurance as well as pacing issue and could be nutrition/hydration.
Two – your pacing is off for all the races because you do not train at the correct paces. The key is to learn goal pacing. When in doubt, simply do time trials to be able to estimate what a goal pace should be for a given distance. Go here to calculate some paces for yourself.
Three – as you eluded to, it could be mental toughness is lacking. This is an entire area to work on. But I can tell you is that if you don’t consistently practice being mentally tough it will not magically show up on race day. You can work on your self-talk. (What do you tell yourself as you have the urge to stop and walk for instance?) You can do practice workouts that are very challenging to put yourself in a position to practice techniques to enhance your mental toughness. (Image certain things, use cue words, use affirmations, dissociate from the discomfort, associate or tune in to your body – are all examples.)
I know this is somewhat general but these are the themes that most likely contribute to your problem. Only by doing things in practice can you really begin to hone in on what is bothering you in races.