Learning to "live in the now" requires meditation & practice.
However when we're always thinking about tomorrow, next week, month, or year it robs us of experiencing peace & serenity of (now). Compartmentalizing while working on goals is the key.
"Grant me the serenity to accept the things I cannot change, Courage to change the things I can, And wisdom to know the difference." - Reinhold Niebuhr
Newsflash! We're all going to die. (That's for certain!)
Life is a (personal) journey. Learn to enjoy (your) adventure!