Watch the Upper Leading Tones online guitar lesson by John Goldsby from Upright Bass Handbook
This exercise focuses on leading tones, approaching from one half step above the root. By leading into the root in every bar, you emphasize the sound of the root. The leading tone, since it's a half step away from the target, has a strong pull towards the root, and it gives your bassline forward motion.
The first chorus through the blues uses one leading tone on beat 4, leading into the root on each downbeat. The second chorus approaches the root with two leading tones, on beats 3 and 4 of each measure. The second chorus leading tones begin two half steps away from the target root. Once you grasp this concept, you're on your way to playing walking basslines, four beats to the bar.