Mdd
Are you joking?
Proof?
Did you ever learn Mesilas Yeshorim, Chovos HaLevavos or any classic Mussar Sefer?
If you’re not familiar with these Seforim, pick one up, open it to ANY page and you’ll have your proof.
And you then ask: if they indeed did exhort Yiddim to work on themselves to perfect themselves in all regards to go far beyond the minimum required by Halacha in order to reach Shlaymus. You ask: “who says it is right?”
There is no answer to someone who can ask that question.