Excerpt from Mark Twain’s Following The Equator:

I can quit any of my nineteen injurious habits at any time, and without

discomfort or inconvenience.  I think that the Dr. Tanners and those

others who go forty days without eating do it by resolutely keeping out

the desire to eat, in the beginning, and that after a few hours the

desire is discouraged and comes no more.

Once I tried my scheme in a large medical way.  I had been confined to my

bed several days with lumbago.  My case refused to improve.  Finally the

doctor said,--

"My remedies have no fair chance.  Consider what they have to fight,

besides the lumbago.  You smoke extravagantly, don't you?"

"Yes."

"You take coffee immoderately?"

"Yes."

"And some tea?"

"Yes."

"You eat all kinds of things that are dissatisfied with each other's

company?"

"Yes."

"You drink two hot Scotches every night?"

"Yes."

"Very well, there you see what I have to contend against.  We can't make

progress the way the matter stands.  You must make a reduction in these

things; you must cut down your consumption of them considerably for some

days."

"I can't, doctor."

"Why can't you."

"I lack the will-power.  I can cut them off entirely, but I can't merely

moderate them."

He said that that would answer, and said he would come around in

twenty-four hours and begin work again.  He was taken ill himself and

could not come; but I did not need him.  I cut off all those things for

two days and nights; in fact, I cut off all kinds of food, too, and all

drinks except water, and at the end of the forty-eight hours the lumbago

was discouraged and left me.  I was a well man; so I gave thanks and took

to those delicacies again.

It seemed a valuable medical course, and I recommended it to a lady.  She

had run down and down and down, and had at last reached a point where

medicines no longer had any helpful effect upon her.  I said I knew I

could put her upon her feet in a week.  It brightened her up, it filled

her with hope, and she said she would do everything I told her to do.  So

I said she must stop swearing and drinking, and smoking and eating for

four days, and then she would be all right again.  And it would have

happened just so, I know it; but she said she could not stop swearing,

and smoking, and drinking, because she had never done those things.  So

there it was.  She had neglected her habits, and hadn't any.  Now that

they would have come good, there were none in stock.  She had nothing to

fall back on.  She was a sinking vessel, with no freight in her to throw

over lighten ship withal.  Why, even one or two little bad habits could

have saved her, but she was just a moral pauper. When she could have

acquired them she was dissuaded by her parents, who were ignorant people

though reared in the best society, and it was too late to begin now.  It

seemed such a pity; but there was no help for it.  These things ought to

be attended to while a person is young; otherwise, when age and disease

come, there is nothing effectual to fight them with....