A myriad, which is literally 10,000, means innumerable. Sort of like when your momma said, "I have told you a million times!" The number 10,000 occurs over fifty times in the Bible (or so I read) and it is just one of those numbers like 3, 7, 12 which convey much meaning.
I have shared in years past my growing attachment to repetitive prayer. It allows one to be present to God with more focus on Him and less on self (and spinning words). Over time, I have combined the practice of praying "thanks and praise" with a rosary. Holding beads is a helpful activity which requires just enough energy to sort of block some distractions. So I began integrating the practice into my life. A few months ago I began thinking of 10,000 and based on quick math realized saying "thanks" to God 350 times a day would produce 10,000 thanks a month (actually a few more) and over the year it would be a myriad times twelve, which seems wonderfully Biblical.
I figure lots of folks never tell our Lord thanks, so it seems fitting to cover for them... Besides, He deserves it and I need a Gratitude Attitude. Being thankful is healthy and helpful. I recommend it. And there is plenty to be thankful for, from big things like creation, redemption, sustenance of the earth to more personal things like health, food, family, friends. Would you miss your skin? Then why not thank God robustly that you have skin. Are you glad to see, or hear, or walk? Thank Him. A good rule of thumb is to decide how much you would complain if something were not there and try to be as thankful that it is. If you lost a leg would you be upset every day? Well, are you a fountain of gratitude each day you waken and your leg is there?
One ministry of the church is worship: praise and thanks. We should do it corporately. We should do it privately.
Which is another reason why I feel sorry for atheists. They do not believe in creatures, because there is no creator. They do not believe in the gift of life, because there is no Giver of Life. When something amazing and wonderful happens, the birth of a child, a lovely sunset, deliverance from distress they can never see a Guiding Hand providing a blessing. How sad and pitiful to never be able to say "Thank you" for so many of the things which matter most, because there is no one (in their mind) to thank and, in a real sense, nothing to be thankful for (things just happen and there are no blessings).
So Christians need to stop acting like atheists, taking it all for granted and not regularly turning to The Heavenly Source with gratitude and praise.
Thank you, Father
Thank you Lord
Thank you, my King and my God
Repeat 10,000 times!