The other key ingredient, IMO, is energy/passion/motivation. Love, if you will.

I'm a songwriter primarily and so I have generally approached guitar by playing my own compositions and honestly, kind of regarded playing other people's stuff as a waste of time. When I started on GuitarTricks, I was doing the exercises and then applying them to my songwriting. That worked and I definitely made progress. But...

I made exponentially more progress when I started practicing chord changes, strumming, etc. with other artists' music that I love, esp the live versions There is something, for me, about playing along with a live track of a favorite song that gives my fingers the motivation to do their best work. Practicing technique by playing along with live tracks is now a regular part of my practice and it has seriously amped up my progress.

There are lots of reasons for this, of course, including the aforementioned energy and passion and love, but a more specific reason is that, I think, playing along with a live track you love allows you to bypass your critical thinking brain and tap into your intuitive self and also your ability to feel your way through the music rather than think your way through it.

There is research to back this up. Our brains don't know, for example, that the events we see on screen are not really happening, and we process cinematic entertainment as if it were a real experience even when our rational brain knows that it's not.. I'm going to take an educated guess that we do the same with live concert recordings (esp if they're on video) -- some instinctive part of our brain tells us that we are actually onstage with the band. And I think that motivates us to up our game so that we can play with our heroes. And I think that's as much a key to mastery as muscle memory. Combine the two and you've got a powerful set of tools in your box.

So in addition to developing muscle memory by just fingering the fretboard while doing other things, consider finding a live track of a song you love that includes those changes (songs in the key of G are very easy to find and no doubt your favorite artists have recorded many key of G songs) and let the music guide your hands.