I don’t think it means something that different from the Chovos Halevavos. It should also be pointed out that the Gemara says that the Shechina is Shora on Simcha shel Mitzva. The proof is from Vayehi Kinagen Haminagen. Rashi says that that was Simcha shel Mitzva since Hashroas Hashechina is a Mitzva.
Since the Gemara is not telling us Halachos for a Navi, it stands to reason that there is some form of Hashra’a on non-Neviim too — as we say, Veruach Kadshecha Al Tikach Mimenu — and which is dependent on being Besimcha. Being Besimcha for that reason is a Mitzva.