Not all practice is created equal.
This is a hard truth I learned when I first picked up the piano. Coming from a background of bluegrass festivals and parking lot jams, I assumed my mandolin experience would quickly and effectively transfer to the piano. I understood a fair amount of theory, so I picked up some Chopin and dove right in!
Needless to say, months passed without making any progress at all. I still felt extremely uncomfortable on the piano, and I was feeling discouraged beyond belief.
Then one piece of information changed my life; I learned how to practice.
Practice is taught to most musicians as a one size fits all system because of the natural progression that all musicians have to go through:
Technique -> Repertoire -> Musicianship
Any person who wishes to be a musician must follow this natural progression, and any person who wishes to be a great musician has to follow this sequence over and over again for their whole life.
But just because there is a natural sequence to musical improvement does not mean that every journey should be identical! This is where we traditionally get everything mixed up!
Practice is a personal journey, and every human should engage with practice as a personal journey.
Intensity is more important than content.
This is the secret to practicing effectively: practice whatever you feel like practicing, but practice it with all of your might.
If today feels like a day for ragtime, practice ragtime. If today feels like a day for pop, practice pop. A day for improvisation should be spent improvising.
As you invest all of yourself into the things that you naturally want to practice, you will start to notice that you need a better understanding of technique to achieve the sound that you want.
Then, and only then, will you be motivated to practice technique in a way that sticks with you.
Practicing what you want with a high level of intensity creates a demand for advanced technique, and you will find a superhuman level of motivation arises from that need.
Practice is a way of life.
One more concept that will change your musical life: break down the barrier between your musical life and your "real" life.
Every moment of every day is musical if you chose to observe the musicality of the world.
What is that bird singing? How would I play that on my instrument?
Is that microwave buzzing a perfect fifth?
Woah! What crazy rhythm did that passing car just play when it bounced on that speed bump?
Can you identify the scales being used in that elevator music? The harmonic progression?
What sound could possibly convey the loving glance your friend just gave you?