In an aish.com article, Rabbi Noson Weisz writes that
. . . contrary to popular belief, Rosh Hashanah is not about reward and punishment. The Talmud informs us that mitzvot cannot be rewarded in this world (Kiddushin 39b). The commentators explain that the physical world simply does not have the resources to deliver the amount of joy required to compensate the performance of even a single Mitzvah.
Only people who do not have the merit to make it to the World to Come are written into the Book of Life to compensate them for their past good deeds; we certainly hope that none of us are in this position. The conclusion: when we stand before God and pray for a good life in the coming year, we are not asking Him to provide it for us as a reward.
But if the judgment we face on Rosh Hashanah does not concern reward, what exactly is being weighed? According to Rabbi Dessler, the model we should study as an aid to understanding the deliberations of the Heavenly Court on Rosh Hashanah is an economic investment model; the judgments of Rosh Hashanah are the heavenly equivalents of earthly investment policy decisions. On Rosh Hashanah it is decided how much Divine energy God will invest in the world in general and in our own lives in particular in the course of the coming year.
The most fundamental tenet of Judaism is that this physical world we inhabit is not our final destination but is merely a workplace. Each of us is sent to this world by God to develop ourselves spiritually and earn our entry to the World to Come, the place we regard as our destination where we shall receive our reward. God’s policy regarding the manner of setting up the conditions we encounter in our working environment, this world, is summed up in the following passage:
"Whoever undertakes to purify himself, we shall assist him. Whoever undertakes to shut himself to spirituality, we shall provide him or her with the opportunity to carry out this design." (Talmud, Yuma 39b)
The direction we choose to follow in our lives and the levels of intensity with which we pursue our spiritual objectives are evaluated annually. If we have made use of the inputs we were given in the previous year and progressed towards perfecting ourselves, the Heavenly Court will generally decide to increase its investment in us. Our circumstances for the coming investment period, the New Year, will be arranged in a manner that ensures that we encounter the opportunities we require to progress even faster toward our goals.
. . . Because the world is recreated every Rosh Hashanah, the day marks the occasion of the establishment of a brand new Divine Kingdom. Jewish tradition maintains that God informed us about Rosh Hashanah to allow us to have some input into how this new kingdom is to be fashioned. The purpose of creation is to allow man to actualize his spiritual potential. As I stand before God on Rosh Hashanah, He is waiting to hear from me about what I plan to do to actualize my spiritual potential in the coming year.
If all that issues from me is my desire to live on in prosperity and good health for another year, I am actually informing God that I do not require the renewal of His Kingdom at all. I am perfectly happy with the world just as it is. But God did not intend this world to be a comfortable place where I merely keep living on and on. He created the World to Come as the place of enjoyment and living the good life. The sole reason for the existence of this world is to provide man with a place in which he can work. If my main interest in being in this world is to live well and enjoy myself, I don’t need to be here at all.
On the other hand if I sincerely resolve to invest my energy (really the Divine energy that I am asking God to renew, out of which I am fashioned) in the coming year into developing my spiritual potential, not only do I need this world to be recreated, I also need it to assume the particular shape that will maximize my ability to work efficiently, and develop as much of my potential as possible.
