These days have been particularly busy and I found myself a little overwhelmed both physically and mentally. I managed to stop the negative thoughts when I felt I couldn't take it anymore and I realized that the problem is that I can't properly manage my time. I should try to work on that.

These past few days have been very busy and I have found it a little overwhelming physically as well as mentally. I managed to stop the negative thoughts even when it felt like I couldn't do it. And I realized that the problem is that I can't arrange/manage my time properly. I should spend more time on that/it. (would be better to explicitly say what you want to spend more time on, in order to avoid confusion for the reader)