The best way to start at becoming a knight was to start early. At
a young age of seven or so, boys were often sent to another castle as a
page serving a family and learning good manners. Playing "chicken" (which
was a game where you sat on someone's shoulders and tried to knock the
other player down) was a good way for a young page to build up strength
for fighting. In the yard a soldier taught taught the young boys to fight
using wooden or blunted weapons. A page's first horse might have been wooden
and have wheels though the boys learned to joust on it.
A growing page learned to ride skillfully on a real horse. He then learned to charge at a quintain which was a wooden target that was sometimes designed to spin around and knock him down if he was clumsy or slow. At about 14 years old the page became a squire his job was to help a knight and battle at his side. After four years of experiencing warfare a new knight would be dubbed. The squire would undergo a vigil before the ceremony which was a night of prayer. Swords and gilt spurs could now be used as a symbol of knighthood.
Becoming a knight was a very expensive process because you had to buy armor and horses though in the end you served and protected your castle to the death.