It's a bit hard to say without knowing more about you as a person, but very broadly, I'd say do things specifically for yourself....do some exercise, treat yourself to things you like, eat well so you feel good inside and take time away from life to connect with yourself....maybe a bit of meditation, or some specific time in the diary to do the things you like to do (hobbies or whatever makes you smile).
And if you like looking after your partner and that makes you happy, then there's nothing wrong with keeping doing that as, if you think about it, it's making you feel good so it is an investment in your well-being.
