This phrase has lost its relevance and power because it has become a boring cliché.
In Tai chi, it is important that your practice doesn’t fit in with “at the end of the day”, a boring repetition that does not bring relaxation. Progression in your understanding of Taiji is important, so it doesn’t become stale and stuck.
If your practice is very simple and you want to keep it that way sure then think about your smile, or the energy you are generating or focusing on the body, are good places to start.
Then perhaps make the hips the centre of attention as they lead the movement, or keeping the head suspended, these are good places for your practice to evolve and grow.
Or perhaps practice feeling centrally stable.
Practice embodying the postures completely.
Practice concentrating as you lift. Practice the feeling of loving kindness both inside the body and outside too.
There are many important principles to follow to ensure your practice evolves and allows you to merge with what you practice.
There is no end of the day with Taiji, there is a natural progression, a personal investigation for you to focus on. So what is important for you today?