If you spend a whole Elul learning Seforim on Bitachon, you will be coming back to Hashem. There was a Yid who did that, a Novardoker. His name was R' Dovid Bleicher Zatzal. He was the star of Novardok; he was the star of Klal Yisroel. He was a bomb! When he learned in Slabodka (before going to Novardok), he was the chavrusa of R' Avrohom Grodzensky Zatzal; there was nobody like him. I was told by R' Shlomo Figer Zatzal that R' Dovid Bleicher had a briefcase packed with Seforim on Bitachon.
And that's what he did all the time. Bitachon, Bitachon. R' Zundel of Salant Zatzal was the father of the entire Mussar movement, the Rebbe of R' Yisroel Salanter Zatzal. What did he work on more than anything else? Bitachon, Bitachon, Bitachon.