The concept of sharing mutual pleasure with Hashem is to find joy in what He wants from you - to perform mitzvot, etc. It reminds me of people's firsts - for example when a person first becomes frum and is passionate about keeping every mitzvah, or when a person works hard to achieve something - such as realizing a chesed project, specific learning, or building a relationship, etc.
I can't think of (aside from the above) where I've felt this type of pleasure with Hashem - atleast not lately (which is probably one of the reasons I'm taking this course!). I think that sometimes it's more difficult to bring our mundane daily acts to the realm of holiness and feel that what we do has meaning. In terms of the things we do outside of learning and specific mitzvot.
Rav Yitzchak Cohen speaks about the key to becoming truly human - by emulating G-d and controlling our animalistic tendencies. How do you understand the concept of 'l'hisaneg al Hashem', to share mutual pleasure with Hashem? Have you ever experienced this feeling?