Actress Jennifer Aniston believes that smiling all the time keeps her happy and slim. The 43-year-old, who is engaged to actor Justin Theroux, has learnt that dieting is no longer important to keep trim, and instead likes to spend time in the sun with a big grin on her face. “I stopped dieting when I figured out that you just have to eat regularly and properly within moderation,” femalefirst.co.uk quoted Aniston as saying. “The fads are too much. I think it’s really about – honestly, this is going to sound silly – going in the sun for 20 minutes a day is really important, vitamin D, because we are now having a vitamin D deficiency because of all the SPF. And I think being happy and smiling and laughing a lot,” she added.