God knew the importance of "rest," so he created the sabbath as a day of rest. He didn't say to sanctify him, he said to sanctify the day. "Sanctify," means to means to bless, consecrate...it means "to set apart."
Your body, mind and spirit need to take a day off...to rest and rejuvenate.
With our busy schedules, we find it hard to rest. "Sunday" is not a day "set apart" for God or anyone else for that matter. We are so busy "catching up," that we don't rest; we don't have, or take, the time to just relax and enjoy life...to unwind.
Stress is a killer; but stress is nothing more than worry over things in the future that we have little or no control over.
I used to work twelve to fourteen hours a day, seven days a week...until one day I woke up in a hospital bed with a stint and two angios in my heart and discovered the wisdom of resting one day a week.
Whatever you do, however you spend it, rest one day a week...it's a whole lot better (and wiser) than waking up in a hospital bed.
If it wasn't important, God would have made it a suggestion...not a commandment.
If you want a happier, healthier, wealthier life: Rest one day a week.