At times, it is possible for one’s connection to Hashem to lower a bit, resulting in a lack of Emunah and anxiety. (Shall it not happen to anyone!) What are some ways to destroy anxiety? Can you list sources in the Gemara or other books that discuss anxiety, and how to cure it? Thanks!
You may want to take a look at Tanya's chapter 29, which discusses how to deal w a situation when one feels stagnant in one's spiritual state (timtum halev), here is a link: https://www.chabad.org/dailystudy/tanya.asp?tdate=2/13/2018 Chapters 26-28 are a very good sources too...
This answer might be somewhat controversial and sensitive but I'd like to give it anyways. If you are male, try to become shomer habris. Stop masturbation and viewing inappropiate things. After 2 weeks all anxiety is gone and you are in a spiritual blissful state.
This is my personal experience. Our sages also amplified the importance of this particular issue and it really does work. HaShem is watching you and if you remain holy, no anxiety will creep in.