Rihanna takes special ''personal days'' to do things for herself.

The 31-year-old singer has said she now makes sure to set aside special days where she takes time for herself, because she doesn't want her career to feel ''like a chore''.

She said: ''I never used to be this way. It's only the last couple years that I started to realise that you need to make time for yourself, because your mental health depends on it. If you're not happy, you're not going to be happy even doing things that you love doing. It'd feel like a chore. I never want work to feel like a chore. My career is my purpose, and it should never feel like anything other than a happy place. I've made little things a big deal, like going for a walk or going to the grocery store.

''I got into a new relationship, and it matters to me. It was like, 'I need to make time for this.' Just like I nurture my businesses, I need to nurture this as well. I'll shut things down for two days, three days at a time. On my calendar we now have the infamous 'P,' which means personal days. This is a new thing.''

And when asked if she actually marks off the days, she added: ''Yes, and it's a different colour than all the other events. I still get harassed on those days, but I'm fine doing e-mails.''

The 'Work' hitmaker juggles her music career with her beauty line and other ventures, and says she sometimes works until the early hours of the morning in business meetings.

She said: ''I don't leave things hanging. I will work all day in a meeting, leave that meeting at 1 or 2am, and then come home with a tiny group of staff and work until 5, 7am.''

And the star values her personal days because she rarely gets enough sleep when she's hard at work.

Speaking to Interview magazine, she said: ''I don't have a sleep pattern. I have sleep pockets. I fit it in when I can. That's why I take those personal days so seriously. Because it's like, 'You had all of me. I gave you the answers'.''