I've been trying to do simple things like walking and making food but I get so tired that I just don't do them. I need energy to do things. I mean I have an apartment which means I need a job in order to pay for rent. What do I do if I can't work? I'm far too exhausted.
For me I find that eating and energy and exercise are all connected. All parts of an essential chain. The trouble is many times depression makes me lose my appetite. I just don't want the hassle of making food and eating. A gradually get tired, lethargic and lose weight.
Recently I'm trying to make sure I eat something. Something easy and basic but nutritious. I pour some oats into a bowl with some almonds. Then pour in some milk and a bit of honey. Leave it for 30 minutes and then eat what I can. Even if it's just a bit, I can always put the bowl in the fridge for a bit later.
Have a peanut butter sandwich. Have an apple (fibrous food which can also help teeth and gums), kiwi fruit. Basic and cheap stuff that packs a lot of nutrition.
As for exercise, that's something that you need to do otherwise it's a downward spiral of tiredness. Just do a bit of exercise. A bit is better than none at all. Walking is good. Also press ups. Just do a a few throughout the day. Little and often.
This is what works for me personally. But even then I can be so down that I have no motivation to eat or exercise.
Hope this helps in someway. Good luck