“I just want to play freely – I don’t want to feel uncomfortable”
Often as musicians, we find ourselves playing challenging material – something that is just a little beyond where we feel comfortable. That’s certainly true as we are learning an instrument. I think it’s also true in other areas: I’ve found while training for my next 10km race, often the running that my training programme requires involves me feeling a bit pushed.
And we can have ambivalent reactions to that feeling of discomfort when playing challenging material. Working with amateur musicians, particularly, I often hear the desire to feel comfortable while playing. People want to play easily – they want it to be flowing. They want to be able to ‘switch off’ a little bit and enjoy themselves. They certainly don’t want to feel ‘on the edge’!
Certainly, we don’t want to be ‘on the edge’ all the time. I think it’s important that we rest, and that we take the time to revisit material so that we CAN take a step back and enjoy our music-making (or training…).
On the other hand, I’ve read some material recently that gives good solid evidence for why playing challenging material – at least some of the time – is important for our growth and creativity.
Playing challenging material helps us gain mastery
When we work on playing challenging material, we are effectively improving our ‘neural networks’. Particularly with complex physical skills like driving a car, playing sports, dancing, or playing a musical instrument, there are too many lines of thought happening at once for them all to be controllable in working memory. When we practise we link parts of the skill together into ‘chunks’ that enable us to streamline how many things we actually need to process. 
Mastery in pretty much any field could be defined (in part) by how effectively the performer in question has created ‘chunks’ that help them carry out their skill. Psychologist Adriaan de Groot found this when he studied the ability of novice and master chess players to recreate a chess board from memory. The masters could do it easily, but only if the boards resembled patterns from a real game. If the pieces were random, they did no better than the novices. The chess masters didn’t have better memories – they simply had more experience of more boards. They could divide what they saw into chunks for easy use. 
If we work on creating chunks of information by consistently working on challenging ourselves with new and trickier material, we can improve our performance, too.
Playing challenging material helps us expand our limits
The improvement of mastery from creating chunks alone can help us expand our limits so that we can do/play more challenging material. But we may be expanding our limits in another way, too. In her book Cure, author Jo Marchant describes the ‘central governor’ theory of physical exertion: the concept that we all have a ‘limiter’ in our brains that prevents us from exerting ourselves beyond safe levels. Many believe that particular kinds of physical training – like short-burst high intensity interval training – help to retrain the central governor so that we can exert ourselves a little further. But what if this is true on a psychological level, too?
Psychologist Wendy Mendes studies the effect of changes of attitude to stressful situations on our sympathetic nervous systems. Mendes has found that, put very simply, how we mentally approach a challenging situation determines how stressed we get. If we look on a challenging situation as scary, we will have a larger and longer-lasting adrenaline response than if we look on the same situation as exciting.
As FM Alexander found when investigating his own vocal problems, we can often have inaccurate concepts of what it is that we are doing. We can think we are doing an activity in a certain way, but actually be doing it very differently to how we imagine!  This is equally true of activities or material we find challenging. What if the challenge isn’t actually in the activity itself, but exists purely in the way that we perceive it?
If, therefore, we accustom ourselves to testing our limits by playing challenging material, we are improving our ability to mentally approach challenge. We will be better able to cope under pressure.
Accept the challenge, but accept it wisely
A bit of a challenge, then, is a good thing. It helps us achieve mastery, and enables us to expand our concept of where our limits might lie. It gives us experience that will enable us to cope better under pressure. Just remember to be mindful that the challenge you accept is also realistic. A newbie mountain climber should probably not choose Everest for their first major challenge. Even a relatively skilled pianist might be biting off more than they can chew if they choose some works by Liszt (or virtually anything by Alkan!).
So make sure the challenge pushes you a bit, and then work at it. The results might astonish you.
 Oakley, B., A Mind for Numbers, Penguin, Kindle ed., p.55.
 Katwala, A., The Athletic Brain, London, Simon & Schuster 2016, p.33f.
 Marchant, J., Cure, Edinburgh, Canongate, 2016, p.80.
 ibid., p.171.
 Alexander, FM., The Use of the Self, London, Orion, 1985, p.33.