Parviz is on to something important here:
The point with the joy in Spinoza and the celebration in Zarathushtra is precisely that it is NOT emotional. It is instead a pure imperative. This is HOW you should view life, this is HOW you should view existence. It is not something you should sit around and wait until you feel it, it is an existential attitude you should decide for yourself that you have. The emotions are out of your direct control but they are are eventually bound to follow with your decision to enjoy life as it is. This is why Mazdayasna is an imperative attitude towards existence and NOT a hedonistic project in the modern sense of "enjoying life" as in "experiencing life as a pleasure". Yasna is all about enjoyment as mandatory and not about pleasure as emotional.