TAOM (and possibly) Shopping.
Shabbos is extremely holy and is the holiest day of the year (it is even holier than Yom Kippur!) It is the day that Hashem so to speak comes down to dwell with us and just be with us. I think the reason you cry on Shabbos is because you are a very sensitive and spiritual person and you are able to feel Hashems closeness to you. I think its an amazing thing to feel Hashems closeness to you and something you should be happy about and thankful for. Many people don’t “feel” Hashem and dont know the experience of feeling close to Hashem or only have it on the rarest occasions. You are from the lucky few (due to your nature and probably because you are actively seeking closeness to Hashem in an authentic and genuine fashion) who can access that closeness more frequently. However please dont cry on Shabbos. We are supposed to be happy joyful and take pleasure on Shabbos not be sad and mopey.