I have a junior that keeps mentioning burn out, and I largely tell them the same thing. Working hard a couple times a year to keep a project on time may be worth it to make a good impression on my boss and make it easier for me to promote you (2-3 things for me to mention is plenty), but you don't want anyone to expect you to continue this long term. Chill 90% of the time and push occasionally to make a good impression, anything more is wasted effort.