what do you do when you feel depressed?

I've been through depression before. Many years ago. But I'm starting to feel like I'm headed down that road again and I'd like to stop before it gets bad. I've started to realize how I've been acting and not caring about anything and this is all how it started years ago. I have gained weight but I still eat shit bc emotions. My house is a mess. I'm slacking at work and school. I'm always tired, clothes are tighter, and I have zero energy. I just need some advice or help from anyone who understands! I should add that I live alone, I'm 35 and have a boyfriend and a dog. That's all.