People are more easily induced to do, and do more easily, what they are already used to; but people also learn to do things new to them.
 John Stuart Mill, Considerations on Representative Government (1861). copy citation

Context

“It would be a great mistake in any legislator not to shape his measures so as to take advantage of such pre-existing habits and feelings when available. On the other hand, it is an exaggeration to elevate these mere aids and facilities into necessary conditions. People are more easily induced to do, and do more easily, what they are already used to; but people also learn to do things new to them. Familiarity is a great help; but much dwelling on an idea will make it familiar, even when strange at first. There are abundant instances in which a whole people have been eager for untried things. The amount of capacity which a people possess for doing new things, and adapting themselves to new circumstances;” source