Every second in a day is unique. Think about it. Every single moment in one day's duration will never happen again on that exact moment of time.
As you are reading this, you might not be conscious of it by seconds have passed that will never happen again. But, in terms of time seconds are not the only concept of time that is special.
Weeks that pass cannot be relived. Once a week has passed we are onto the next one, same with months and years.
So ask yourself this, how does one live each second, day, week, year and so on to the fullest? That depends on what makes you, as a person, happy. What I try to do is try to make every person I meet smile at least once. You might ask why I do this, the answer is simple.
You never know what type of day that person is having and by making them smirk or grin you might have made their day better or if not that one second. That’s better than nothing right?
Of course you do not have to do this, I was giving an example. But, why not try to smile or giggle at something silly knowing that lame joke or weird picture has just made you live a moment in time that will never happen again?
Also, I would like state in my opinion, this is valid until a working time machine is invented and we as a people can actually relive the past.