I think you just listen to your body. When you roll over in bed and feel like you can get up for a while, even to sit in a chair to read or watch tv...you do it. When you feel up to a little cooking you do it to have it in the freezer for when you don't. Even when I'm having a bad time I get up once an hour during daylight hours to walk back and forth across the house to the bathroom, the kitchen for tea. Being still too long is dangerous for blood clots, and such.
So, do move, a few minutes an hour and then a few more and when you get to a spot where you say - hmm, I've been moving around for 2 hrs and I'm not bad - then perhaps you can think about going to work. But when you hit the wall at a certain time up and moving you know you need to stop there for a while.
Some days I'm up for 4 hrs sitting on a stool in the kitchen working, some days I'm in my wheelchair pushing myself around because my legs get heavy like yours...but my arms are ok so I can do little things like laundry (sloowwwly). I have found that accomplishing something each day helps me to not be as depressed. I'm also taking GABA, and it's not helping pain but it is helping my mood. I've read that folks like us are very low in it.

ps, the kitty in my pic? Her name is Luna - she keeps me company.

Love that you cat is called Luna :)

"...dont want to rest too much...".
This is not possible to do :)

Everyone is so different. Keep experimenting, to see what helps. Some days I would push myself and not crash the next day, as was the case. Sleep if you can sleep, and think happy , healing thoughts. It's amazing how rested your body can become. isabelle1854

What do you mean by "pushing oneself" ????

It means disregarding what your body is telling you.
Your body is telling you to rest, and you carry on regardless.

I try to cut back all that I can of the types of activity that make me worse. We just do what we can. The right balance comes from learning to listen to your body. Of course all of us willingly ignore the body's messages at times. Good luck.

It's really, really hard to know how much is too much. There are no warnings or red flags, like muscle pain, to send you a message.

You just gotta rest, and not worry. If you carry worry into your rest periods then you're not really resting. Helps if you believe in God and can let him do the worrying for you.

Yeah, "pushing it" is when you make decisions based on your left-brain intelligence instead of your intuitive reading of your body. Best advice I can give you is if you don't feel like doing something, then don't do it.

I've had CFIDS for decades and still haven't figured it out. Don't blame yourself; don't push yourself. You're up against a bad one where there are few answers.