Just like you're voyager 1 or something! :D
But I pretty much faced the same problem when I started. Feeling exhausted, or not quite awake. And yep, only excecise helped. It seemed doing 10 to 15 minutes a day got my body going. Not even every day actually. I got a dumbbell and just did different exercises. Not to exhaustion, just as much as I felt comfortable, which obviously slowly increased over time. At some point I realized I got quite some biceps, to a point where it started to look ridiculous compared to the rest of my body, since I got down to 70kg.
I have found pretty big differences in response even across short timescales. I was able to shed 30 lbs last year with severe calorie restriction(240>210). This year my 5'11" body is not so cooperative (220>???).
Exercise seems to be a no brainer even without a weight concern but I’ve been a lazy fuck all my life when it comes to that so I hoped a calorie deficit would work as well again.
Now, that was 10 years ago, I slowly gained weight again but not to the same degree.
I started the same diet a month ago, at the age of 40, I can not lose weight this time. It is really interesting, I just get exhausted. It's like my body decided not to burn fat but simply shut some stuff down instead. Had some blood tests and stuff and there are no glaring issues.
I guess this time I need to exercise. I wonder if it is age or something else entirely.