The weather may make you feel run down to a point so it could be that. Get some more sleep at night. Your only eating 3 meals a day that wont cut it, cant you make up 2 protein shakes while your at work. That will give you 5 meals right there.

If you cant make it through a workout you may need to switch it up try less volume, try lifting eod, dont take everyset to failure.

Just some thoughts