I'm 40 (I think age is important when measuring productivity of IT workers) and I can do 12 with a lunch break; however, I will be a zombie next day and half-zo

I'm 40 (I think age is important when measuring productivity of IT workers) and I can do 12 with a lunch break; however, I will be a zombie next day and half-zombie the day after. I do two long runs per week b/c it hurts my brain not to finish a module/task plus I hate to 'reload' the problem in my head the next day. Also, having the feeling of 'not done' makes me unable to disconnect from work and rest. On zombie days I do the no-brainier tasks or catch up with emails. Not sure if this a good strategy but I feel that in the long run I accomplish just as much.