Today's DIY was so quick and simple that I'm kicking myself for not doing this sooner. It seriously took maybe 20 minutes, and that mostly was because I was super picky and my sewing machine was being finicky.
This could be considered a Valentine's Day craft, but I picked strictly non-V-day colors so it could be worn year-round. It'd look great either way: your choice!
The supplies couldn't be simpler: Shirt that fits you well and fabric for the heart (my heart fabric came from a too-short sequin shirt, but any contrasting fabric would do!)
I cut a heart shape out of the sequin fabric (like elementary school, folding it in half and cutting out a mirror image) and pinned it in place on the shirt. A quick pass through the sewing machine, and I was done! Cute, right?