I just started a STEM PhD before last christmas and whilst things are going okay, I still feel like I'm not good enough and don't deserve the opportunity. I guess it's some form of imposter syndrome but it's driving me to become irrationally attached to my work because I lack confidence that it's good enough to impress my supervisor.

I consistently overwork myself and as a result my personal life is suffering- I even feel bad about taking weekends off. None of what I do feels like it's good enough and I constantly feel like a failure- I have a presentation in the next few weeks to present my project progress and I'm dreading it.

How do I ditch this mentality?