Yes, I know the conversion. I simply want to make it so instead of milliseconds being shown in the serial monitor seconds are displayed instead. I am having trouble trying to define "millis()=millis()/1000"
Not I. I want to know approximately how many seconds have passed, to the closest value.
I tend to consider, for example, 1.999 seconds as 2 seconds, but to each his/her own. People certainly do lie about their ages, often truncating much, much more than 6 months.