"I'm really opposed to specific exercises. You see piano players who sit and tap their fingertips individually on tabletops all day. You see bass players who take a rubber band or a hand grip. It may give you strength, but it does not give you control; I may not have the strongest physical hand, but I have the ultimate control of all my fingers independent of each other. For me the key word is finger control rather than strength. Today bass players have been caught up in raising their strings a little higher than normal to get a bigger sound and make their hands stronger. All it does is make their sound less attractive. It makes the sound much harder, but it tires them quickly.
"Besides, when a string is that taut, it cannot vibrate to its normal length, because the note is physically shorter. The decay period for this note is shorter than if they were to lower the bridge, say, an eighth of an inch. When the string is not so tight, it vibrates much more freely and is much longer. This makes the body of the brass, which is nothing but a big sound chamber, vibrate at much more frequent vibrations, so you get a much warmer sound. This is my thing. I try to get as warm a sound as I can and use as little physical effort as possible to produce it."