Thank you for your question. God is all-Merciful, Wise, Just, Kind and Powerful. There is nothing outside of His ability and nothing can resist Him. If a person tries to reflect on His Attributes they will put their hope in Him and be optimistic in Him. There is a hadith from Imam al-Hasan (as) where he speaks about a believer always being in the best situation (for himself). Whether that is a situation of difficulty or ease, the believer puts his hope in God and through God-centricity uses every situation as an opportunity to get closer to Him. At the same time, humans still need to work according to wisdom, the system of cause and effect and to live religion such that they can put their trust in that relationship they have with God. The more they are doing their part the greater their hope in God. God is most Merciful so there is no stage where one should not be optimistic about Him, and when a pessimistic attitude is taken or indeed a neutral view of God, that is the beginning of mistakes.
May you always be successful.