I don't get down in the dumps too often, when I do it's normally because I'm feeling insecure, or like I really messed up, or I just couldn't care less about well... anything. On days like these It's important to go easy on myself. Here are some tips for when you're feeling crappy.
1. Be by yourself - I'm in introvert, so maybe this only applies to us, but I hate being around people when my bad mood. Besides my mood just rubs off of people putting them in bad moods (I'm horrible at faking a good mood). Snuggle up with a book, or doodle or journal. This works especially well if people are what's frustrating, or making you feel insecure.
2. Paint your nails - Pamper yourself! If you can afford it go have your nails done, but if not just put on a coat of a forgotten nail polish. Forcing yourself to sit there and let you nails dry gives you a little moment of peace, as if nothing in the world matters more than holding completely still to not mess up your top coat.
3. Feel pretty - Painting your nails may go into this one, but you'll feel so much better about yourself if you put a little effort in in the morning. It doesn't have to be something extreme, just something to make you feel better about yourself. A little lipstick goes a long way, I rarely wear lipstick, and when I do I always feel a little special.
4. Sleep - You probably need it. There's nothing I love more than waking up from a nap. If you can't squeeze one in, at least try to go to bed an hour or so earlier. And on top of that drink some water, being tired and thirsty are major mood killers. I carry around a water bottle with me at all times to prevent dehydration (and the headaches that go with it). You owe it to yourself to take care of your body, and when we've got a lot on our plate our health seems to be the first thing to go.
5. Jam - Change up your usual playlist while you're working, driving, or working out. Music can really set your mood for the day. Consider burning a CD (yeah an actual CD) and put it in your car for when you're feeling blue. Over time, you'll feel better when you play it, give it a cheesy name in sharpie like "Feel good Mix" and pretend we're in the 2000's.