adobe illustrator - How to modify path width?

I have this image of a heart:

favorite.svg

and this image of a back arrow:

back.svg

I would like to modify the line width of the back arrow to match the line width of the heart. Any ideas on how I can accomplish this in illustrator?

Answer

If the artwork was just a stroked path, @Scott would be right. But from what I can see when I look at the SVG files, they are filled shapes:

See the nodes in the corners?

So you will need to Offset the path by a negative amount:

Object -> Path -> Offset Path

To end up with a thin arrow

Or, just scale down the arrow until it has the appearance of line thickness that you like, but it won't be at the original size anymore.