At the beginning of the book, we learn a little about Gulliver, and about his decision to travel. We learn that Gulliver was born to a family that is quite poor, and is therefore unable to keep him. Gulliver travels to London and becomes a surgeon's apprentice. He dreams of travelling, and this motivates him to become a surgeon aboard a ship called The Swallow for three years.
Hi motivation changes after he settles down. He establishes a business and gets married. However, his business in London begins to fail and his patron dies. He then goes to sea again and travels for another six years.