I can find to peace in mind when I write a diary, read books, and listen to play piano.

= I can find peace of mind when I write in my diary, read books, and listen to piano music.

Especially, when I am stressed or have a hard time, doing these things helps me find peace.

= Especially when I am stressed or going through a hard time, doing these things helps me find peace.

Comment: Thank you for writing, Seon. Study harder!