The actress received tremendous critical acclaim for her performance in this year's blockbuster Bridesmaids, but McCarthy told Parade that she wasn't always so lucky.
"I think everybody should wait tables, because you get the best and worst thrown in your face," she said. "People would lash out at me, and I just thought, 'I'm working so hard. Why are you yelling about a vodka and tonic?'"
McCarthy added that the struggles of her young years have made her all the more grateful for the way her life has turned out.
"I feel like I got hit with a lucky stick," the star declared. "I have the greatest husband and two little girls who make me crazy - in a good way - and I love what I do for a living. What's there to be blue about?"
Her sitcom Mike & Molly airs Mondays at 9.30/8.30c on CBS.
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Watch a clip from Melissa McCarthy's recent appearance on Saturday Night Live below (US only):