Life in the developed world is made up of 30,000 days or 82 years.
It is a very small number if you think about it. At retirement, a 65 year old has 17 years remaining, with around 5 of those years restricted by a severe or profound limitation. Every single day is so important. Life is over in a flash.
Now is the only time there is. I might wish I was young again or I might wish there was something I did or said, but it is not going to bring the time back. There is only one time. And that time is now. Make it count.