The videos below showed up in my Youtube sidebar so I watched them since I had the day off. I have to say this was very eye opening and maybe it just clicked since I have been drilling major & minor triads so much and trying and failing to improvise decent bass lines to play with chord sheets. Anyway, after watching this video and following the guidelines I played a little and was like... hey that sounds decent! So I went to guitar pro and wrote out a walking bass line about 24 bars long over a ii V I progresion and while not great it did not make my ears bleed. If you are interested I don't think it can be explained much easier than in these videos. I'm sure it can get a lot more complicated but this video is like a gateway drug to walking bass line addiction. It has probably been linked before but throwing up here in case someone else wants to check it out.