Bella Hadid is ''really hard'' on herself.

The 18-year-old model has admitted she would ''cry'' when she didn't get a job in the past but insists sister Gigi Hadid is her rock.

She said: ''I've always been really hard on myself. If I didn't book a job, I would cry ...

''Gigi really helped me. She would say, 'It's not about you.'''

And if the siblings model side by side on a shoot, they always make sure they have a good time.

She added: ''During one shoot, we literally sang Broadway songs the whole time.''

Meanwhile, Bella has admitted that she and mother Yolanda Foster are amazed by her success.

She shared: ''My mom and I were Facetiming the other day and she said, 'It's so crazy how much you've done in such a short time that others don't get to do in a lifetime.'

''It was a really gratifying moment because I look up to her so much and since I've started modelling, it hit me. I love this and I want to do it for a really long time.''

And because of her international fame, Bella has had to keep up her profile on social media despite it getting too ''personal'' sometimes.

She told Editorialist magazine: ''I used to post a lot of me and my friends but it got really personal. Now I just try to base it off of work.

''Back in the day, you really had to hustle, but these days you don't need a portfolio. You can just look up someone's Instagram.''