No matter how old you are - excluding possibly infancy - there's always the chance of your back tightening up, especially if you're doing some sort of lifting, exercise, or other strenuous activity.
If you're "on the go" like most Americans seem to be these days, you simply do not have time for this.
Here's a stretch that can at least ease a little bit of that tightness.
This is just one of the many ways to stretch out your back.
Tightness in your back - especially your lower back - can really impede your progress during the day.
For all of my fellow factory workers out there, this one is for you.
I know what it's like having to lift things all day, and what a literal pain it can be when there's even just the slightest tightness in your lower back; it can make your entire shift painful and grueling.
There's nothing "sissy" about stretching that beast out before a long shift, and it can give that back of yours a few extra years if done properly.
Lie down on a flat surface - the floor works great for this - bend your knees, and put your feet flat on the floor.
Put both hands on the bottom of your thighs and slowly pull your legs toward your chest, pulling until you feel a slight stretch.
When you do feel that, hold that position for at least 15 seconds, or for as long as you can.
Slowly return your legs to where they started, and repeat this exercise eight to ten times, or until you're exhausted.