All the virtues build on each other, so I've been pondering gentleness from that angle. What are the vices that might keep me from being gentle? What does it take to be gentle?
The first vice that comes to mind as being opposed to gentleness is selfishness. If I am thinking of myself and what I want, then I will be harsh and impatient when interrupted. If, on the other hand, I am thinking of how I may serve others, then I will be quick and cheerful in meeting their needs. After dinner I usually clean up the kitchen. If, while I'm doing that, I'm thinking of myself (I'm tired. I want to go to bed. I want to sit down.), then I will leave the job half-done, doing just enough to keep the dirty dishes from taking over, and I'll take twice as long as I need to accomplish it. If I'm interrupted in such a frame of mind, I'm likely to delay and frown as I respond to whoever needs my attention. If, however, I'm thinking of others (If I set the timer on the coffee maker, then my husband will have an easier time getting up in the morning. I should sweep the floor, so that the baby won't try to put anything yucky in her mouth tomorrow morning.), then I move more quickly, do the job more thoroughly, and if interrupted, will respond more promptly and cheerfully.
Similarly, pride will prevent me from being gentle. If I am proud when I encounter an inconvenience (like the person in the parking garage driving really slowly ... he'll make me late for my appointment! How dare he!) then I will be incensed because of the infringement upon my "rights." I may speak harshly either to the offender, if he is available, or to everyone else around me if he is not. If I am humble then I realize that the big bad world doesn't owe me a thing (and if I'm late for my appointment, then I should accounted for unexpected delays and left the house earlier) and I will remain calm.
In order to acquire the habit of always being gentle I should learn to keep my thoughts in a generous, humble vein. When I start to feel impatient, I should respond by thinking of the needs of others (remembering, of course, that I also have a duty to meet my own needs; I am unlikely to be gentle to anyone if I am exhausted and cross.)