Good at maintainance or good in maintaining

Vctory OngCan I say,

My teacher is good in maintaining/ at maintainance, so she looks younger to his real age.

Many Thanks in Advance

- No

My teacher looks after himself/herself so he/she looks younger than his/her age.

ALso get the pronoun straight.

He/ his

She/ her

Thanks

But isn't that look after means take care of sb.
What I want to express in this sentence is my teacher eat healthily, live healthily and use good face cleanser and sun block and so on to keep himself younger.
Many Thanks in Advance

Hi

Vctory OngBut isn't that look after means take care of sb.

Yes - look after = take care of someone or something. You can also look after yourself.

If you look after yourself it means that you try to have a healthy diet, you try to keep fit and stay in good shape.

Thanks

Vctory OngCan I say,

My teacher is good in maintaining/ at maintainance, so she looks younger to his real age.

Many thanks in advance.

The word is wrongly spelled. It should be maintenance.