The 26-year-old model has confessed her 29-year-old friend is her role model, as she manages to juggle her career and being a mother to three-year-old Dixie Pearl Followill - who she parents with her Kings Of Leon frontman husband Caleb Followill.
Martha said: ''I really look up to her; she's a good role model for me. She's a mom and this super- successful model, and she also has this great sense of style. Also, she's really kind. Every time I hang out with her I like her more.
''(The Victoria's Secret Angels) have to support one another. It's this weird microcosm that we're in together, so we have to be there for one another.''
The Victoria's Secret Angel - who had back surgery for scoliosis after graduating high school - went on to insist that even though she trains ''really hard'', she doesn't want to be ''too thin''.
Speaking to the Hamptons Magazine, Martha said: ''You don't want to overthink it; you want to still be yourself, but you want to be the best version of yourself. I work out, train really hard, and eat healthy food. You don't want to be too thin; you want to be fit and a good example of a feminine woman's body.''