Depending on what music you’re playing, and on what your goals are for your lessons or independent study, you are likely playing technical exercises and pieces. Even technical exercises can be played musically, but it’s understandable if you find playing exercises at the piano less interesting than playing pieces.
If you are playing exercises in addition to pieces, one piano practice organizing technique is to start each session with a warm-up of scales, followed by exercises, and then working on repertoire (the pieces that you are learning).
Dividing each practice session into sections like this, can help you to stay regular with *what* you practice — ensuring that you are covering everything you intend to cover in each session — while helping you to organize your time and structure your piano practice, such that each session has an order to it. Of course, not every piano practice session has to have an order to it! You might set aside days when you simply play whatever you want to play at the piano, rather than actively working on a piano piece that you are learning. As an adult learner, you are most likely taking lessons or studying on your own, for enjoyment! So take time to simply enjoy making music!