Count it all joy…when ye fall into manifold temptations;
Knowing that the proving of your faith worketh patience.
The temptation (tests, trials) are not of God (James 1,13).
But then how can I count it all joy, if the devil is trying to finish me off?
How can I rejoice in midst of my sicknesses, depressions, terrible finances, lusts,…?
Important is that you shouldn't rejoice over the temptations, because they are of the devil, but instead over the possibility to resist/withstand in faith (that is the meaning of patience), because God works in that process to give you the victory.
To be patient means to stay strong (withstand) in faith and to not let go of the promises, until they are visible. You can only practice that kind of patience in faith though, because faith calls those things that are not (invisible/spiritual) into the visible realm!
That is how you can call your healing, prosperity, peace,… from the spiritual realm, where you already have every spiritual blessing, into the now, so that you receive them and see and touch them with your physical senses.
That is exactly what James is saying in those verses. You shouldn't enjoy the temptation by itself, for it has its origin with the devil, but you should rejoice in their midst, for you can withstand and resist by faith, so that you bring all the blessing from the spiritual realm into the NOW, until you are perfect and entire, lacking nothing.
Furthermore, you should rejoice, because as long as it is in the realm of faith and patience, the blessings are not limited in how big they can grow.
That means that with every day that you are resisting, they keep growing and growing, getting bigger and more beautiful, until they are so great and wonderful, that they are truly heaven on earth once they manifest.
Because of that, rejoice if you still have to withstand and resist. Your blessing is growing and growing, until it will break through to the visible realm, if you just don't quit. And once it broke through, it will make you perfect and entire, so that you lack nothing.
You should count it joy, when you are put to the test, so that you have to work your faith and practice patience/withstanding/resisting, for the reward that comes with it cannot be compared to the short period of withstanding in faith that you have to do now!
Withstanding in faith is a time of joy, because as you are withstanding the devil, you are growing and growing, until you finally overcome the trial and come out victorious, perfect and entire, lacking in NOTHING. With this amazing end result in mind, you can rejoice, despite whatever you are facing right now!
(James 1,2-4 & 2. Corinthians 12,10)