Twenty-one days, defined and studied by Christians, Psychologists, and Numerologists all to mean very different things as referenced above. What do you believe? The only way to truly know is to work through 21 days of something. This is not something that you can read and decide for yourself - try it. Do something different.
I started out doing something different for 21 days - I planned to go without bread, sugar, rice, and oil. I made it just about to the end, but fell off due to celebratory events. None the less, I did something different for about 18 straight days. Did I lose a pound, no. Did I gain a pound, no. Did I gain confidence in myself, yes. Do I feel better, yes. Perhaps in the 21 days of restraint and my already daily prayers was synonymous with the Biblical Fast and Prayer which is why I gained a greater lesson during the 21 days. (Note: A prayer has been answered during the 21 days although my intent was not to fast and pray for it.)
Sometimes the thing that you set out to learn from doing something is not what is in store to learn. My hope was to lose a pound or two, instead I gained something greater - a stronger will. One that I often negated as possible. My next adventure 1-hour of cardio exercise daily for 21 days. No breaks. Healthy? Nope. What is truly healthy these days? Let's just see what I learn from this...stay tuned.
Regardless of the lesson outcome, my point is to try something different and learn something from it. Trying something new - something different doesn't always mean to go parachute out of plane. Sometimes trying something different means to just take a few baby steps outside of the baby walker we call our daily lives. Try it - 21 days of doing or not doing something - you never know what you might discover.