Exclusive look: Inside Olivia Culpo's fitting for tonight's Go Red for Women Red Dress Collection

Olivia Culpo will join over 20 celebrities tonight to walk the runway in support women's heart health, and it'll be a glamorous evening to be sure. The American Heart Association's Go Red For Women Red Dress Collection presented by Macy's will feature these famous women wearing custom-designed gowns by leading womenswear designers. Forever in an effort to bring awareness to the number 1 killer of women, heart disease, we're thrilled to see so many powerful women join with Go Red For Women to help educate us all on heart health.

Plus -- they'll be wearing really incredible gowns, created just for them. A little fashion and a little awareness -- what could make for a better evening?

We got an exclusive sneak peek into Olivia's fitting day leading up to tonight's big event. She will be wearing Marchesa, so we know her look is going to be beyond beautiful! Olivia walks us through each moment of her fitting day, below. Click through to see!

Go Red For Women is the American Heart Association's national movement to end heart disease and stroke in women, and for more than a decade has fought for women's equal health opportunity. Click through below for full coverage of the runway show -- every single gorgeous red look!

More in style:
13 bloggers to follow this NYFW
BCBGMaxazria plays it cool in color and design
Elie Tahari explains the 5 items you need for New York Fashion Week