This is a super simple DIY if you need a last minute Valentines Day decoration:
I found a photo of a heart garland and since it wasn't accompanied by a step by step I came with how to make it on my own. I used regular colored printer paper in two colors. Fold each sheet in half the long way and then cut strips about 1/2 inch wide. The fold is what makes the "v" at the bottom of the heart. Then using a glue stick add glue to the outside top of one side, bend into the middle and press against the opposite strip of paper. That will create the dimple at the top. Just keep alternating and linking (or just use one or even more colors if you so desire) the hearts together until you get the length you want.