Occasionally I will describe my concerts to someone as primarily 'opening up a window into the land of no troubles'. As simplistic as this sounds, it is likely the most apt description I have heard, in terms of the why and the what...
It is possible to think of spirit as only enthusiasm - often a welcome approach to those with grave misgivings around organized religion. A deeper look will find that the roots of the word give it a context - 'en' means 'within' and 'thusiasm' is coming from the Greek 'theo', meaning God. So, enthusiasm means to have God within...
It is very much as if playing music with enthusiasm is all one need do to make it a spiritual practice. Of course this means never getting bored or frustrated while playing, as these states are only possible in the absence of enthusiasm...!
So how to avoid these lapses of enthusiasm? Since my own approach has been led by the heart, my own way could be described as 'chasing beauty'. If one listens closely while playing, one will always hear if it sounds beautiful or not. And from here, it is a direct step to only playing if it sounds beautiful, even if it means playing just one note, then two, over and over, as long as it maintains that beauty.
If one perseveres in this approach, eventually the obstacles of self-judgement and impatience will be surpassed, and everytime one plays, it will open up a window into the land of no troubles.
It might be referred to as the fine print to mention that the only way I can see to harness the personal energy required to maintain this focus long enough is to commit to living a good life in a spirit of gratitude and service to your community. :-)