Patience: This is going to take some time. Playing a musical instrument is, in a large part, an athletic event. Like getting back in shape, sustained effort over time wins every time.
Enjoying the journey: Musicians love to practice. In fact, that is what it is all about. Sitting at the piano is a joyous act. Learn to enjoy the little things, like an evenly played scale, a beautiful phrase ending.
Organization: Pencils, recordings, ear buds, phone to record ourselves, some quiet time, and a plan on how to use that time.
Review: Spend some guilt-free time just playing stuff you love and play well. Over time this list will grow, like a garden. A list you will be proud of.
Keeping the inspiration well filled: Get out there. If you live in a city of any size, there is a music community of like-minded adults. Join them. Chat after concerts. You'll meet other adult musicians, make friends, get together and play duets. In short, have some fun.
You've got to learn your instrument. Then, you practice, practice, practice. And then, when you finally get up there on the bandstand, forget all that and just wail.
I'm a professional pianist and music educator in West Toronto Ontario. I'm also a devoted percussionist and drum teacher.