My question is related to acquiring God given wisdom. Prophet Muhammad (s) said: “The person who devotes himself sincerely to God for forty days, streams of wisdom will flow from his heart to his tongue.” [Al-Suyuti, al-Durr al-Manthur, vol.2, p. 237].

1- How does one devote himself to God entirely? Are there any requirements? I feel as though keeping away from sin, and fulfilling ones obligatory requirments isn’t enough. I feel like there is something missing.
2- How to accuire sincirety in prayers? (prescense of heart) There are some prayers where I seem to have strong connection to Allah, and the next prayer all of a sudden I dont.
3- I have heard that if you are not able to cry during salatul layl, you should atleast pretend to cry, is this true?