There are many dangerous perils on the quest to destroy the ring of power, not only in the form of evil wizards and orcs and dark lords, but also in the form of real-world conditions like dehydration and hypothermia, which only makes it all the more remarkable that Frodo and Sam managed to get all the way to Mordor without being detected by the enemy, but also without succumbing to the other terrible and painful deaths that could have awaited them.
This in part thanks to the generosity and kindness of friends who helped them along their journey, like the elves of Lothlorien who gave them the Lembas bread that helped them survive many hungry nights, and people like Faramir who gave them a good meal and a package of food and water to take with them when he released them from Ithilien. But the other part relied on keen survival instincts, and at least a little bit of knowledge of how to survive without the comforts and seeming necessities of home.
There are many characters who are very good at this, including Gandalf the wizard who was always able to use his magic to create a fire for light and warmth, and Aragorn who, as a ranger, had spent many nights out in the wild, learning the lay of the land. Once Frodo and Sam depart from the other members of the fellowship though, they must rely only on each other, and to a certain extent Gollum, to help them survive all the hazards that lie ahead. It becomes very quickly obvious that among all of the hobbits who set out from The Shire, Samwise Gamgee is the most equipped to help them endure the terrible conditions that they must face, because he possesses surprisingly good survival skills for someone who has never ventured further than Farmer Maggot's fields.
There are two significant reasons as to why this is. The first is because of the class system in Hobbiton, and how each hobbit of the fellowship falls into their categories. Frodo and Bilbo are of a particularly wealthy and prestigious breed of hobbit, from a long and illustrious line of Harfoots. Merry and Pippin are both related to this line as well, and are cousins themselves, so they all share this jovial sense of privilege that Sam doesn’t have.
The young Gamgee is Frodo’s gardener, and his family has worked for the Bagginses for generations, hence why he always refers to his friend as ‘Mr. Frodo’ or ‘sir’. As such, Sam has had to pick up a lot of practical skills and tricks that the other have never needed, such as how to care for horses, how to tie incredibly strong knots, how to catch game and cook it, how to keep calm in high pressured situations. He is therefore essential in keeping Frodo alive during their quest, as he is stronger from years of manual labor, and more level-headed than the upper-class hobbits who struggle to even leave home without their handkerchiefs.
The other element to Sam's success in the quest to destroy the ring is that he was always an adventurer at heart, far more than the other hobbits. At the time that Bilbo has to leave, he tells Gandalf that ‘in his heart, Frodo is still in love with The Shire’ and this is fundamentally true. Frodo doesn’t leave Bag End because he is craving adventure and wants to explore the mysterious domains of Middle Earth, he leaves out of a sense of duty to Bilbo, and because it is no longer safe for him to remain there. Merry and Pippin too, have never been afraid to explore around local areas like the Old Forest, and the Prancing Pony in Bree, but have never had particular designs on setting foot further afield. Sam however, has always been a dreamer, and grew up enamored with the stories that Bilbo told him of the elves in the trees, and slaying dragons.
Samwise paid attention to the little details, absorbing as much information as he possibly could, which unknowingly helped him in his own adventures all those years later. He was brave enough to fight for what’s right, and smart enough to think of interesting ways around serious problems, because he had been preparing for these trials ever since he was little, without even realizing he was doing it. His heart, unlike Frodo’s had yearned for adventure, and so, when he heard of the dangerous quest, he was the quickest to volunteer himself to accompany and protect his dear friend. Without him, Frodo almost certainly would have perished, and the ring would have fallen back into the hands of Sauron, which would have cost the whole of Middle Earth it’s freedom.