No. It's not. It's because I am termed an "exceptional responder" and the cancer in my body is reacting in a very favorable way for now.
While I am a naturally optimistic person, being so didn't prevent the cancer to begin with, nor does it have an impact on how treatments impact the cancer. While being positive may help my quality of life, it does nothing to extend my life. Additionally, I definitely have crappy down days where getting out of bed is difficult.
The positivity myth is one that needs to be knocked to the curb.
Here's a study on the topic that proves that having a positive attitude has absolutely ZERO impact on cancer survival.