If it's a school project that got you down in the dumps, take a couple of hours off. If you have the time a few days is even better. If it's school in general that is dragging you down, take a semester off. Reevaluate what you're going to school for. If it's really that dreadful, maybe you're not going to the right reasons or are trying to force yourself into the wrong field. When you find the thing you love, you'll love learning about it.
An extended break from a relationship is probably not going to work in your favor. Step back, take a weekend to yourself. Go on a solo vacation or spend time on your own for the weekend. Though you may think your friends give amazing relationship advice, make your own decision. They're not in the relationship - you are. If after a couple of days you aren't feeling it still - break it off. Don't tell him that you're taking a relationship break when you take some time to yourself. Breaks are not good news. And do you really want him thinking he has a free pass for the weekend? I think not.
If you don't have money in the bank, start looking for a new job before quitting. If you have a couple months worth of rent/bills saved up. Just up and quit. Find a job you love or move across the globe for a few months. The world is at your fingertips. Don't waste your time working a job that you hate. If it's just been a few bad days, take a sick day. Binge watch some Netflix, enjoy a bubble bath and a glass of wine. You'll go back feeling refreshed and better than ever.
Blogging (or Writing...or Art)
When it comes to anything somewhat creative if you're feeling blocked don't force it. I recently found myself uninspired and in a blogging rut. I took a few weeks off and I'm back with a totally new set of eyes. I'm ready to change my branding and switch up my content. I now know what I'd like to share with the world. Taking a couple months off between seasons of my podcast is also amazing. We get to discuss where we want to go and how to make our format and content better. It doesn't have to be a long-term break, but if you feel like you don't know what you want to draw or write or say, step back for awhile and breathe. Go do something else and come back to it when you're ready.
Taking a break isn't a sign of failure, but if you force yourself to do something that you're not proud of you can easily become one. Listen to yourself and know when to stick it out, when to take a break, and when to know you're done for good.