I love life and no matter the age I would do anything to continue on. Be grateful for treatment as it will give you opportunity to enjoy your life. You will get through it. Have you had any counselling? Some people get a bit depressed with cancer treatment so be careful you're not sliding down that dark place. Life is so great if you want it to be and treatment is there to give you that life. You could get through this and be fighting fit for years.
I think we have all wondered why do it. I think will all wonder about getting through treatment or not doing treatment but as someone who did treatment and unfortunately now is metastatic, I have no regret and I will go on and keep having treatment for the rest of my life. I am 62 and I am hoping I live for many many years and they find many more treatments for me. Best wishes