Joyous prayer is certainly greater and better received before HaShem, blessed is He, than a prayer of sadness and weeping.

An analogy for this is as follows: Although a pauper begs and petitions the king with much weeping, nonetheless, he is only granted a small gift. In contrast, when the governor of a province comes before the king, and recounts the praises of the king with great joy, and while doing so, also puts forth his request, in his case, the king grants him an abundant gift, as is befitting of a governor.