NSV - Borrowing my skinny aunts work out clothes!

So I've had the same old, crappy work out clothes since I was about 20lbs heavier and 2 sizes bigger than I am now. Today my aunt was going to an aerobics class and asked if I wanted to come with. I of course said yes, but that I had no work out clothes that fit properly. She said she'd lend me some of hers, but I was sceptical about whether they'd fit or not; she's maybe 0.5/1 inch shorter than me, but she's always been really slim. Anyway, I said I'd try the clothes on, and guess what? They fit perfectly! The top is an XS and the bottoms are an S and they fit me just fine. Success!