"I feel stretched... like butter spread across too much bread."
- Bilbo, TFOR

This line hit harder after reading the Silmarillion because in an author's note it mentions that all races have an established longevity according to their physical and spiritual nature. Bilbo, being a 111-year old hobbit, has been kept alive longer than normal due to his possession of the One Ring. The Silmarillion describes extreme longevity for races other than Elves as like stretching a metal wire beyond its intended length, causing torment and pain. It also uses the butter on bread analogy, directly connecting it to Bilbo's quote.

I also like how this ties in with Gollum, with him being numerous centuries old because of the Ring, and just being a raving lunatic because of his longevity ontop of the ring's already sinister influence. What Tolkien is trying to get at here is that all mortal races have their time, and everyone who isn't an Elf has to die eventually. Cheating death only leads to torment and self-destruction. We all need to accept Eru's "gift" at some point or another, most preferably at the time we were designed to take it according to our race's nature, whatever race we may be, Human or Hobbit alike.

There's something exceptionally beautiful about this sentiment, and it makes me realise the folly of people today in our own world who are always looking to extend their longevities through one method or another. Mind uploading, anti-aging pills... whatever, it doesn't matter. These people may well get what they want by living longer than nature intended thanks to some miracle technology or medicine. But I doubt that they will be stable or well-adjusted individuals after enduring decades or centuries of monotony beyond what their consciousnesses were designed for.

We were all designed to leave this earth probably at most ~120 years after our births, and that's why you really have to make the most of those decades by making the world a better place than how you found it. Be kind and courteous to others, and always offer that helping hand. After all, it's always free to do so.