Put it simply from what others said, frustration will always follow you as you decide to work on a box or any other target. Always remind yourself that HTB is a learning platform. The issue is the way you take it. You get frustrated, you close the laptop and go cry feeding yourself with thoughts “I will never get good at it”, or you get frustrated and go take a break smiling. For some people frustration can be just consequence of damaged self-esteem after they realize they don’t know something. Just accept you aren’t obligated to know everything in this world - and moreover you cannot, and just go with the flow.