Beyond all great deeds there is a force that drives them. For the men and woman that accomplish those deeds their is something within them that gives them reason to continue, and to labor for their goals. Aragorn was not unlike those that go to great lengths to accomplish a goal. There was an ever-present driving force within him.
Within the third age of Middle-earth there would have been little to no hope if Aragorn the Ranger had not accomplished the tasks that he performed. Surely darkness would have consumed Middle-earth, and the fourth age left under the dominion of Sauron. For what purposes did Aragorn do the deeds he accomplished, and where all his goals selfless?
Aragorn first appeared to the hobbits as Strider, the cloaked wanderer, and certainly a conspicuous figure. Even then the wanderer carried the blood of Númenor within him. For many years he had already defended the land against Sauron, and protected the Shire from unfriendly eyes. His deeds for a long while went unnoticed, but they were all calculated towards his goal, his driving force behind all his actions, to be the king, to return Gondor to its former great strength, and to be wed to Arwen Evenstar.
Aragorn grew up in the house of Elrond till he was twenty years of age. He then left after meeting Arwen for the first time. They fell in love, but Elrond would not allow them to be wed, not till Aragorn was king. For ninety years he then labored, for the king, and for the love of Arwen.
The deeds that he did that are detailed are within the Lord of the Rings, and a short period of time. Though his labors are far more vast, and much of him remains as mystery. The first of Striders accounted adventures is with the four hobbits, whom the ring bearer is one. Facing dark riders, unfriendly lands, and battling time, he successfully lead the hobbits to Rivendell. After he was within the fellowship of the ring, the nine adventurers that set out on the quest of the ring.
From this quest Aragorns greatest feats were made. After the fall of Gandalf, Aragorn became leader of the fellowship, until its breaking. After this he both fought in the battle of Hornburg, the series of battles outside of Minas Tirith, and the battle outside the black gates. As the heir of Isildur, Aragorn lead an army from the paths of the dead to Dol Amroth. From there he battled the corsairs and sailed a fleet to the aid of Minas Tirith, turning the tides of battle. This was Aragorns greatest of deeds, and showed the true power of his will.
From the time we see Aragorn first appear as Strider, to the time when he receives the crown from Gandalf as King Ellessar, his character changes a great deal. Slowly he reveals himself as the noble man he is. This is shown through subtle changes in his appearance, and the magnitude of his deeds.
Behind all that was done and accomplished in the life of Aragorn, there was that driving force within him to continue. As the heir of Isildur he was the rightful king, and he earned the crown with a lifetime of hard labor, and valiant deeds.