London: R&B star Rihanna's month long vacation turned into a sour affair because of her anxiety about work.

The 24-year-old 'We Found Love' hitmaker was headed to the Hawaiian Islands with a group of friends but now she says the time away was torturous as she was preoccupied with career concerns, as reported.

"I kept feeling like something was not getting done, like I was being irresponsible. I knew this was going to be a big year, and I felt like I was not doing anything about it. I had such anxiety, I was going crazy," Rihanna said.

However, the singer admits there was one daredevil activity she enjoyed on her holiday and that was swimming with sharks.

"You have no idea the thrill. Let me ask you something. When you know you like a guy, or when you have been in love - that feeling when you see that person, what is it like? Is it the same feeling you have on a roller coaster?

"That is the same feeling you have swimming with sharks. That is the same feeling you have when doing anything daring, risky, spontaneous, or unpredictable. I think having those butterflies is the closest thing to being in love," she added.

(Agencies)