Melissa McCarthy thinks she'd have gone "cuckoo" if she'd found success earlier.
The 47-year-old actress got her big break in TV show 'Gilmore Girls' in 2000 and she will always be grateful for the years she had to "struggle" because it's made her more appreciative of what she has.
She said: ""When you spend 20 years working your butt off, you know yourself better. If you're handed everything you want at 19 or 20, you may actually believe all of the people who are like, 'You're amazing.'
"I think I would have been probably cuckoo [if I'd been successful] at 18. I think the best thing I could have done was struggle until I was 30. I always assume every job is my last. Twenty years of desperately trying to get a single job gets deep in your DNA."
The 'Bridesmaids' star - who has daughters Vivian, 11, and Georgie, eight, with husband Ben Falcone - believes a lot of her success is down to luck, rather than something particularly "special" about her.
She said: "I have a very, very high level of gratitude. There is not a single day that goes by that I don't think, I can't believe I'm doing this.
"And there is no world where I confuse the fact that I've gotten lucky with the idea that there's something special about me. I think entitlement is a really, really scary thing to possess.
"For me, it's like, 'No. I've gotten lucky, and I've worked hard.' "
While Melissa is enjoying success and working on projects that excite her now, she admits she wouldn't hesitate to take on less appealing ventures if she's paid well enough - but she'll still work hard for her money.
She told America's Glamour magazine: "I think everybody has a rate for when [your gut is saying], 'Why would I do that? That's not interesting.'
"And so you name a crazy rate to make somebody go away. And then, if they are like, 'Sure!' you will literally own the moon after this - you just have to shut up and do it...
"I've been lucky that in the last 10 years I've only taken things I had the highest hopes for, but the time will come when I'll be like, 'Does anybody need me to sell cheese slices?' Because I'll do it. Just give me a paycheque. And I will work really hard to sell those cheese slices."