Started playing recently and I suddenly realised I've gone quite a way into the game without dieing. This is unusual for me in any game. So I was thinking can I realistically set myself the goal of completing the game without dieing? Or should I prepare for inevitable failure?

It's very possible. Stimpacks are VERY easy to come across, and it's not uncommon to come across having 200+ at a time.

Well, of course it's possible, but depennds highly on the difficulty level you play at. If you are on Normal or lower, and you have ok armor and powerful weapons, you'll do much even without stimpaks (with alot stimpaks its IMO too easy, but I recommend keeping 5-10 with always). There's no much insta/fast-killers in the game, you'll have to aware only Deathclaws and Super Mutant Overlords (if Broken Steel installed) and of course Behemoths. Try to avoid traps too (there's no much of them though).

If you play higher than Normal, you'll gonna be VERY skilled player if you're aiming to no-deaths. Especially if you face Deathclaws... it's simply an insta-death without powerful weapon, armor or good sneak skill to sneak out fast. You also have to take a closer look at the environment, everything there could harm you bad or kill you. if you play on this level, I highy recommend to keep Stimpaks with (you can have them alot here, if you face something deadly you don't probably have time to even think about healing when you're dead already).

Uh. You don't really need alot of skill to play this game on higher difficulty. It's just a slower process. I actually find it easier because if you use a stealthy class, they die alot faster due to higher difficulties being "more realistic"

I play with self-imposed restrictions.... I can't carry every weapon and armor out there, along with infinite amounts of ammo, so I die a lot. It's great really, forces more creative gameplay. And some of the deaths, while a pain in the ass, are quite hilarious or epic.

There is no shame in not wanting to fire a 1000 rifle rounds into an albino radscorpion. I never play on really hard difficulty these days. I've nothing to prove after spending at least 500 hours in the wastes.

Think I died once due to a car explosion, apparently they are all still loaded with gas even after a nuclear holocaust. Wastelanders don't need any gas for all their generators ..... Ahem .... Anyway that's the only time I died and I've played it for over 400 hours or so now, in multiple playthroughs of course. Oh and one time due to being ambushed by a deathclaw which btw made a nice brown spot in my undies, gotta love that

stealth/sneak whatever you wanna call it and accurate aiming and gun control (ie: no spraying bullits everywhere)
got me to level 30, on very hard w/o using any stimpacks or dying. so yes its possible.

and BounceDK..
the cars do not use GAS. it uses Nuclear Power.

when i first got the game, i died a lot. now i seldom die in a gaming session. once you have learn how to play and won the game a few times, try playing an iron man game. when your PC dies, game over.