Use a timer
Why? A lot of anxiety is created by uncertainty. Being unsure of what you’re going to practice and how long you will need to practice for is a great way for your brain to find excuses that mean you might not practice at all. Planning out your practice is one thing, but how do you know you’ve worked on something long enough to move onto the next thing? Perfectionists like me will always have trouble letting something go and feeling satisfied, so might get stuck working on a particular passage or exercise even if that’s not the passage or exercise that most needs to be worked on right now.
Changing the criteria for when you will move on is a good way to get around this problem. Using the timer on your phone to divide your practice into chunks of ten or fifteen minutes (or less!) gives you a clear indicator of when you need to pack up and move on. Improvement will better come from revisiting that passage tomorrow, rather than trying to take it from zero to concert ready in this practice session right now.
Another advantage is that if you’re feeling really anxious about practice you can set a timer to say “I will just practice for half an hour”, and then you have an external guide to when you can stop. This really helps when you are having a hard time getting started on any practice, and works especially well if you think of a reward for when you finish (”I can check tumblr after I do 30mins of practice”, for example).
What? Nearly all phones and computers have inbuilt timer functions. Pre-plan your 10/15/however many minute blocks by thinking about what most needs your attention, then set your timer for the block length and get started. When the timer rings, stop what you are doing, wherever you are at, then restart your timer and move onto the next thing. If you need more time to work on something, make a note in your practice notebook and schedule another block in your next practice session.
Alternatively, you can use a Pomodoro timer to work in bigger chunks of time. There’s heaps of these available for free as apps on your phone/tablet. The idea behind these is 25mins of work followed by 5mins of rest, which helps your brain take a refresher before you get back to it. Personally, I would do a maximum of three of these sessions in a row before taking a longer break (at least an hour away from the instrument), simply to prevent overuse injury.
Be careful! There are two potentials for slip-up here. The first is if you set yourself a task that is too difficult to complete in 10mins, leading to frustration. Avoid this by keeping the tasks very simple and achievable – you’ll find out what this is for you after a few sessions like this, but for example, drilling a particularly difficult 2-bar fragment every way that you know how (instead of a difficult 16-bar section). The second is the danger zone between 10min (or 25min) practice sessions – you need a little extra discipline and effort to push onto the next thing on your list. Look out for that, and use rewards to keep yourself going.