The best fix of low iman is getting Knowledge. Get Knowledge. Don’t just listen to lectures absorb them. Don’t just read books, ponder upon each line.
Learn, Learn and keep on Learning. Wallahi, the more you know about Islam and Allah, the more your heart will soften up. The more your eyes will remain wet.
No knowledge is trivial. Each and every single line of knowledge has a 10 pages of detailed explanation to it.