Jennifer Aniston ''doesn't give a crap'' that people think she's unhappy because she hasn't had a baby.

The 43-year-old actress - who is dating actor Justin Theroux - revealed she is happier than she's ''ever been'' and hit out at ''very narrow-minded'' people who just assume the opposite due to her lack of kids.

She said: ''That doesn't measure the level of my happiness or my success in my life, in my achievements, in any of that.''

Despite being three years into her 40s, Jennifer - who was recently reported to have said she wants to get married by the end of the year - admits she ''feels great'' and still gets ''excited'' every time she has a birthday.

Speaking in an interview with 'CBS This Morning', she added: ''I feel like I'm 30. I honestly didn't start to feel my best until was in my 30s. Physically, I started eating better and taking better care of my body, in terms of being physical and exercise.

''I think it's important every year to celebrate your birthday and be excited about it. I'm 43 and it's great!''