This could vary for many reasons or emotions, including but not limited to:
• Someone looks at you weird.
• You think your significant other is mad at you even though they're not.
• You see a touching commercial.
• You see anything with an animal in it.
• Someone compliments you.
• BECAUSE YOU KEEP DROPPING EVERYTHING.
• Then you stub your toe.
• You're trying to friggin' write a post for the company you work for, BuzzFeed, and it's just not turning out right, and nobody likes it, and then you post it and all these commenters say, "Fail," "Fail," "Fail." Then your mom texts you that you should do a post about the "cash cab" but you just don't have time and you start to cry.
*All reasons are perfectly normal and acceptable.