Excessive Activity, Tiredness and Depression

Recently I've been increasing physical activities such as exercising and doing house chores. One of the reason is I want to lose weight. I target around 3 kg per month. I put 3 kg but I think it is a bit high, but then I might lose 2 kg and that is okay. 

However I think recently I have been pushing myself too hard. I feel tired everyday. And now I feel too tired, but not much pain. And my mind goes blank. And I feel a bit depressed. And blank. And too tired to move. 

I don't know. It may be my fault. I must not put high target in doing everyday activities and exercises. It backfires me. 

I think I need to be more lenient about exercise. Maybe 4000 steps are too much for me. I will decrease until 2500 steps of brisk walking first, maybe. And continue doing house chores. 

I'm really tired now. I wish I can sleep after this. Thank you for reading.