What advice did the doctor give to the writer?

J., the narrator, relates this incident to us in the opening chapter of Three Men in a Boat. He appears to be a hypochondriac who worries that he has every disease and malady known to mankind. Once when he expresses his concerns to his doctor, the man gives him a thorough examination and writes him a prescription. Without even glancing at it, J. takes it to a pharmacist to be filled. But the man there found it impossible to comply, because the note recommended:

1 lb. beefsteak, with
1 pt. bitter beer
                  every 6 hours.
1 ten-mile walk every morning.
1 bed at 11 sharp every night
And don’t stuff up your head with things you don’t understand.

The doctor understood what was going on in J.’s mind. And J. tells us happily that he has followed these directions and has been living well ever since. Except for his most recent concerns about his liver, and his “general disinclination to work of any kind,” as he read of one of the symptoms in a liver-pill advertisement.