Serena Williams works ''on the road''.

The tennis star has been super busy but makes the most of her time on the road by forgoing sleep for her work.

Speaking about her new clothing line, she told People magazine: ''I just work, I don't sleep and I work on the road. I finally took that leap and I have invested in myself and I did it. I always tell my friends, you have to invest in yourself, and I have to take my own advice. I did that, I was like this is what I want to do and we're going to be successful at it because I believe in me and what we do. If we do it right, it's going to be good.''

But Serena always makes time for her 12-month-old daughter Alexis Olympia Jr.

She wrote on Twitter: ''319 days since I gave birth to this amazing baby @OlympiaOhanian I've spent 319 of those days with her. I'm so fortunate. (sic)''

And Serena previously confessed she cried every time her daughter did in the early stages of motherhood.

She said: ''It's tough in the beginning. The baby's crying all the time and you don't know why - you don't know if it's gas, you don't know if she's sick, you don't know if it's just colic. So I just started crying with her because I couldn't help her and I wanted to help her and I couldn't, so I just started crying.''

And her admission comes after she revealed she prayed and ''cried a little bit'' when she stopped breastfeeding Alexis.

She added: ''I literally sat Olympia in my arms, I talked to her, we prayed about it. I told her, 'Look, I'm going to stop. Mommy has to do this.' I cried a little bit not as much as I thought I would ... After [I stopped breastfeeding], like literally I lost 10 pounds in a week. It was crazy. I just kept dropping. I was like, that's when I learned that everything was different. Sorry to go on about that. I wanted to say that so women out there know that's not true. Everyone takes things different. I think it's important for us to share that message.''