Thus, when I observe, if I am cold when I get into a carriage in a morning, I may ride all day without being warmed by it; that, if on horseback my feet are cold, I may ride some hours before they become warm; but, if I am ever so cold on foot, I cannot walk an hour briskly, without glowing from head to foot by the quickened circulation; I have been ready to say, (using round numbers without regard to exactness, but merely to mark a great difference), that there is more exercise in one mile's riding on horseback, than in five in a coach; and more in one mile's walking on foot, than in five on horseback; to which I may add, that there is more in walking one mile up and down stairs, than in five on a level floor. 

The two latter exercises may be had within doors, when the weather discourages going abroad; and the last may be had when one is pinched for time, as containing a great quantity of exercise in a handful of minutes. The dumb bell is another exercise of the latter compendious kind. By the use of it I have in forty swings quickened my pulse from sixty to one hundred beats in a minute, counted by a second watch; and I suppose the warmth generally increases with quickness of pulse. (To @William @Franklin, August 19, 1772)

MORAL ALGEBRA. When difficult cases occur, they are difficult, chiefly because while we have them under consideration, all the reasons pro and con are not present to the mind at the same time; but sometimes one set present themselves, and at other times another, the first being out of sight. Hence the various purposes or inclinations that alternately prevail, and the uncertainty that perplexes us.

To get over this, my way is, to divide half a sheet of paper by a line into two columns; writing over the one Pro, and over the other Con.