Most of us play piano without any feelings. They just press keys as strong as they can. They want the whole song to be loud and straight. They play with only one metronome value and one dynamic. BUT THIS IS NOT RIGHT.
True pianists APPLY VARIATIONS. They put different dynamics and speed. Similar to singing, playing piano should have feelings. Feelings may be happy, sad, lively, sorrowful, energetic etcetera.
Here are the things to do while playing piano:
1. Always sit at the edge part of your chair.
2. Always sit straight.
3. FEEL THE SONG. You may listen to the song with headphones or earphones while playing.
4. RELAX your hands. Put some grace in it. Do some grace lifts.