thanks, I asked just from the angle of when younger we dont tend to think twice about falling off a bike, or at least I didnt anyway. I can completely understand being apprehensive about busting something with a fall, and frankly not wanting to go there completely.

again, I would just suggest doing some practice stuff, with gradually and incrementally increasing your braking power. Thats the great thing with gradual increase of stuff, the changes will happen slowly and there will be no surprises. I still remember clearly being on a racetrack for the first times and the advantage there being that you take the same corners over and over, so by gradually increasing speed through a corner, you can slowly get up to the point where a tire begins to slide, and by being relaxed about it you start to get a feel for when you reach teh edge of traction and not overreact (and cause more f_ups)
On bicycles, Ive found stuff to happen a lot faster, just less rubber patch on the ground I guess, but at least for goofing around with purposely locking the rear and starting to get comfortable with that, its less scary than any front end shinanigans.
In a straight line brake test for example with the rear skidding, you probably have to steer into the slide a bit, or slightly back off when it locks to get the rear in line again--at least the chance of falling is practically nil--it locks, back off rear brake lever, voila.
The hard braking test stuff again is all about gradually increasing the braking power, and with time we start to develop a better feel for modulation and feel of the brake lever--specific to your bike, its brakes, tires, surface and all those variables.

I'll end this with a variation on the old theatre saying, (don't) break a leg ;-)