Bruce Lee is not a runner, he's a martial artist, so I don't really see what the deal is here. Secondly...

the route that Bruce, Kareem (and now I) had jogged was only three-quarters of a mile each way – a total of only a mile and a half. Not a huge distance by any stretch, but then, if the intensity (as provided by the hills) is adequate, you really don’t need a huge volume of such training to solicit a dramatic cardiovascular response. Again, remember Bruce Lee’s point that regarding the nature of cardiovascular adaptation:

The other way [to train one’s cardiovascular system] is progression; you must start out slow and then gradually build speed as your conditioning improves.

In other words, such training has to be progressive and intensity (the difficulty of the exercise) is a factor that can be altered on a progressive basis through a process of either adding weight to your limbs while your running or by increasing the grade upon which you are running.

The Roscomare route is obviously an example of the latter (although, in reading Bruce’s training diaries, he would also do a form of double-progressive running, by adding up to 15 pounds of resistance to his limbs while he was running these hills!)

Quoted from: LINK