Faith / Emuna in G-d takes time. A person lives a more fulfilling life with Hash-m than without. He or she sees the hand of G-d. He or She is never alone. They always have Hash-m to turn to for problems, concerns or prayer.
A great book on the subject is “Living Emuna” by Rabbi David Ashear. He tells stories and gives Torah guidance on how to gain emuna.
I was recently listening to a Shiur / Lecture on the subject by Rabbi David Ichay in French. He told the following story:
Once someone asked the Hazon Ish – a Great Sage of the past generation – how can one gain emuna. He said “When you go out to buy shoes – ask Hash-m to help you find the right store. Ask Him to help you find the right pair. Ask Him to help them to have your size.” As Jews we don’t just turn to G-d when we are in desparate need – but even for the small matters as well. This is how we build belief – this is how we build a relationship.
If we put our trust in Hash-m we can overcome any concern.