I think the thing to remember is sport (like life) is inherently unfair. There is no such thing as a level playing field, and whatever decision on whatever aspect will benefit some at the expense of others.
Also, Israel has an army with a centralised command and control system. If it fires a missile then it's a direct result of a governmental wish. Palestine doesn't have an army, it has a variety of different people launching missiles who at any given time may or may not choose to follow a cease fire agreed to by Hamas.
" Instead I'm thinking how I could just stop, and walk to the finish line,"
I'm pretty sure everyone gets that - and the rest too. Think of things that you know everyone else typically gets in a race - lack of breath, muscle pain, fatigue etc. You know everyone else get's these irrespective of if they are faster or slower than you as you can see it in there bodies. You can't see the self doubt, but everyone's still suffering from it as much as lactic acid. So what do? Accept the mental discomfort just like the physical discomfort as signals from your body that it would prefer not to do what you currently want it to do and carry on as best you can, or don't race.