I think basically all swimmers would agree that we wouldn't wish a 4IM upon our worst enemies, and that we all really just want to be sprinters. Well, here's exactly what I think during basically all the events I swim. The fact that I don't swim breaststroke, 200 IM, or 100 fly was too painful to write about and was thus not included.

400 IM
1st 50 Fly: Okay, cool, things are going great. I can do this. Yeah red. Yeah green. Life is fantastic.
2nd 50 Fly: Hmm, it seems I may be going too fast at this point. Whatever, I'm sure it won't catch up to me anytime soon.
1st 50 Back: Wow, you know, I really hate backstroke. Who thought it would be a good idea to swim, but like on your back? This is stupid. Maybe if I get out no one would notice.
2nd 50 Back: Nope, everyone would notice. They would notice because you are a barge, you are a barge among yachts, and there's no way that you're going to finish this. Life is bad.
1st 50 Breast: WAIT, NEVERMIND, I CAN SWIM AGAIN. I CAN DO THIS. FUCK THE HATERS.
3rd 25 Breast: On second thought...
4th 25 Breast: All systems are failing, I repeat, all systems are failing. Do not swim into the light. Light means actual death, not just the metaphoric death you're currently experiencing.
1st 50 Free: You know what, maybe you should've actually died while you had a chance.
2nd 50 Free: *Delusional mumbling that could not be deciphered*

200 Fly
1st 50:Hey why am I scared of this event? This isn't bad at all!
2nd 50: Wow this is going amazing, I'm on top of the world! There's nothing I can't do! I AM GOD! BOW DOWN TO ME PEASANTS.
3rd 50: I DON'T THINK YOU PEASANTS UNDERSTOOD WHAT I JUST SAID YOU'RE SUPPOSED TO BE BOWING DOWN TO ME, NOT PASSING ME.
4th 50: Am I going to finish? Find out next time on Lost.

100/200 Back
First Half: Nope, don't want to be doing this. I don't even care. Like how bad could this possibly go.
Second half: It could go very poorly apparently. No. You know what? Maybe everyone else is just going really fast.
When I see my time: Hey, not that bad. (If I was nine years old).

500/1000/1650 Free
Entire Event: Hmm, what could they really do if I were to get out right now?

50/100 Free
Entire Event: Ugh, why am I not a sprinter? I hate my life.