How can I tell if I’m burned out?

I actually didn't realise I was burned out until six months after being burned out. So my first startup, I decided to leave it aside after a year of trying and the following six months, just the usual, just take a contract to pay the bills, trying to get back in shape and just not being able to focus on anything. I would've just spent this time, working on my side projects or doing stuff or learning new things but I couldn't do anything of that. I was just like, "It's gone." The idea of 'work is not work, it's just what I naturally do', it wasn't there anymore. Work became that thing that I had to do to pay the bills. And it struck me when I stopped doing it. I was like, "That was the time where I couldn't do anything even if I wanted to do it." I would sit down, be like, "You know what? Now I would look at what new things people have built."

And I would just scroll through it two minutes. I was like, "I don't care." So I think it's a different thing because people don't realise, I didn't realise what was the actual meaning. I thought once you have the energy and the will and it's something that you are meant to do in your life, it'll be there forever, but it's not. So you have to be very careful to keep that flame, that spark, that something that motivates you every single day, because that's basically what drives everything else.