Why did the three men decide to go on a boating experience?

The three men decided to go on a boating experience because they believed that they were overworked and needed rest.
Chapter 1 begins with J., the narrator, discussing how he is prone to many dangerous diseases. His hypochondriac tendencies, however, escape him. Meanwhile, his friends, George and William Harris, are equally adamant that they suffer their share of debilitating illnesses.
In the end, all three decide that a change of scenery would refresh their minds and invigorate their health. However, they initially disagree about where they will vacation. J. suggests that George pick a quiet "old world spot," far from the "madding crowd." William then suggests a sea trip, but J. disagrees. He argues that a sea trip is only a good choice when one has a few months to spare. Since they only have a week, a sea trip would be a disaster.
The three men then argue about the disadvantages of a sea trip. In the end, George suggests a trip up the river. Finally, the three men agree that this is what they will do for rest and relaxation.