“Keep your eye on the ball.”

Basically, you should remain focused on your goals and dreams. With the success of fulfilling them, you can find that you are not easily distracted, or easily discouraged when you pursue more difficult goals.

Thoreau sure has a nice way of saying things…

“…and endeavors to live life which he has imagined, …” = and works to lead his life as though he will (or has already) accomplish those goals

” …he will meet with a success unexpected in common hours.” = he will be successful in ways that no one expects to be while living.

Paraphrased: “If a person moves toward his goals, confident in them and works to lead his life as though he will (or has already) accomplish those goals, he will be successful in ways that no one expects to be while living.”

“common hours” = normal life. “Common” refers to ‘ordinary,’ or even ‘shared.’

Another key term is ‘endeavor.’ It’s “work,” but with an kind of morality about it, as if one stakes one’s honor on what one is endeavoring toward. So, the simple synonym = ‘work,’ but there’s a “connotation” to the term, also, that speaks to how moral/ethical a person’s work is.

Raking leaves is ‘work.’ No moral/ethical connotation there.

Raking leaves throughout the neighborhood to get enough money to buy a new Gameboy is ‘work.’ There’s a simple, personal motivation there.

Raking leaves throughout the neighborhood to earn extra money to buy textbooks for college is an ‘endeavor’ (used as a noun here, instead of verb as in quote) because advancing one’s education is widely accepted as a noble goal, exemplifying good morals.

Hope this helps.

I am not sure what they mean by common hours. Maybe that you will achieve them faster than the average person.

I would say it means if you keep working towards your hopes and dreams, you will be able to attain them in ways that even you didn’t expect!