I hear ya! We all go through ruts in both progress and motivation. I too like to read and watch documentaries on my favorite musicians. You may find you can relate to them on some level.

When you feel unmotivated, think back to what got you excited in the beginning. What has changed?

What are your goals? Make sure that what you are doing on the guitar is helping you get to that goal.

Goals change...perhaps yours need some tweaking. Make sure you have smaller goals...ones that are attainable.

To use myself as an example, my motivation for playing hit a low for a few months. My duo gig was on autopilot and I just couldn't motivate myself to learn new songs. I looked at my duo gig and realized I missed playing more challenging songs in a larger group. I created a BandMix profile. A band contacted me for an audition. I had to learn 7 songs. I had my motivation back...I wanted this gig. I worked hard...and landed it. Now I have more songs to learn than I can count LOL. I'm motivated like I haven't been in years.