Bob,
Just a few thoughts....
As long as people have started analogies to running, walking, etc., I figure I'll throw my 2 cents worth in. My perspecitve here will be related to training for a marathon, of which I've ran 3 (nothing spectacular from many people's perspectives, but I learned a few things that might apply here).
First of all, just completing a marathon takes a certain amount of commitment and a certain level of training. In order to develop that level of training I have found the best way is to have a training plan. This training plan works on an overall goal (i.e. completing the marathon within a specified time) and then it breaks the goal down into various training phases that attempt to accomplish certain things.
Running a marathon is not a sprint (well, at least not for me). However, many of the mechanics involved in sprinting are the same as the mechanics involved in running for hours. So, some of my training consists of sprints. These training sessions usually occur about once a week. During these sprint sessions my main focus is not necessarily on speed, it is on trying to understand how to run more efficiently. The natural result of increased efficiency is increased speed. Sprint sessions also occur over various distances for each session, i.e. week 1 is 100 meters, week 2 is 200 meters, etc. up through a "sprint" distance of 1600 meters. This cycle takes about a month to complete; then the cycle repeats. I have yet to complete a cycle like this without having my time drop in each subsequent cycle.
Another typical running work out is a concept called fartlek training. This concept deals with non-standard intervals. In other words, you're out running down the road and you decide to "pick up the pace" for a bit. Then you back it off and keep running at the prior "comfortable" pace. Over time, the comfortable pace slowly increases.
There are many other "workouts" but the gist of any workout is to isolate a particular part of your running technique so you can focus on it to the exclusion of all the other running variables (in actuality you're almost always working on more than one thing at a time, after all, every workout requires a certain level of concentration on your breathing).
"Long runs" are the time where you put together all of the variables from the different training phases and you work on them as a whole. Since the long runs are at a slower pace than the other training sessions, you shouldn't have to "think" as hard about the variables and you can just run.
As with any analogy these ideas can fall apart under sharp scrutiny. However, the main points I want to make are:
Have a specific plan/goal - this may seem trivial, but I have found that specific, written goals carry with them an immense amount of power.
Speed training ought to be cycled. As the distance increases over which you're trying to "sprint" the speed "must" decrease. However, the next time you come back to the shorter distance you should be able to increase the speed. Also, the idea of the training is not to increase speed, but rather to increase efficiency. Better efficiency automaticlly leads to better speed.
Final point, I am not a world class marathoner or piano player. Take my thoughts for what they cost you to read them

Jef