One of the great challenges for every guitarist is to train the hands to follow directions. Any musical gesture requires a series of targeted movements, placing specific fingers in specific places. Some gestures are much more difficult than others, but ultimately playing any part is just a matter of knowing where you need to land and having the control to make it happen.
This is a really powerful perspective to have, even though it’s a bit of an oversimplification. What it means is that there’s no mystery to how to accomplish anything on the guitar. The instrument is a mechanism, and so are your hands. You might not have the ability right now to do the things a more accomplished player can, but you’re using the same basic tools. Yes, we’re all proportioned a little differently and that can have an impact on what you can and can’t reach. But for the most part, hands are hands and guitars are guitars!
What this really means to you is that you should view any technical challenge as a puzzle to solve.
When you find something difficult to play, break it down. You should be able to identify the specific elements of the part. What fingers do you need to use, and where do they need to go? Are your fingering choices smooth and logical? It’s possible to beat your head against the wall for weeks struggling with a part and then realize that there’s a much easier way to play the same notes. This is where one of the challenges of the guitar becomes an advantage. Since so many notes duplicate in different places across the neck, there’s almost always more than one way to play any given part. The right fingering can make a difficult passage easy.
Even if something is way beyond your ability, there’s real value in at least understanding how the part is played.
You might not be able to reach a particular note or play a part up to speed, but if you’re clear on what the hands have to do you’ll be able to practice in a much more targeted and powerful way. This makes it possible to learn to play songs that are way above your baseline skill level, if you’re patient and methodical enough. Practicing is a process, and taking mechanics into account makes that process much more effective.