Don't Think Too Much
One way to ease the challenge of trusting in Hashem is by minimizing the amount of thinking. When a person thinks too much, its very possible that a thought which is contrary to bitachon will pop into a person's mind, and then will be entertained in the person's mind as well.
This is easier when a person is simpler as opposed to one with great intellect, but it really helps everyone, none the less. We see this highlighted in the following occurrence. Hershke was a simple man, who supported himself by dealing in the market place. He 1 would go meet the sellers of wares a few hours before the market would begin, and get a good rate and then later resell for a profit.
One day, a Maggid came to town who spoke to the crowd about bitachon in Hashem, and he discussed the topic 'that no one can take away livelihood from another', for Hashem gives each person what they are suppose to receive. The Maggid was heaven fearing and his words were well taken and internalized by Hershke. The next day was a market day, and while he would usually wake up early to be the first to negotiate with the goyim with wares, that day he decided otherwise.
What ever was destined for him he would receive in his house as well, because no one can take away what was destined for him. When his wife saw that he was staying in bed later than the usual, she encouraged him to get up. He responded, "Do you know what the Maggid told us in shul? No one can take away business which was destined by Hashem to be mine, so therefore why do I need to go out in the cold and the snow, to go greet the goyim? Hashem can send all of the business here to my home just as well."
His wife didn't handle that well, and she started to give him an earful, "The Maggid will get paid for his nice inspirational speech, but that doesn't mean that you have to sit here doing nothing." He didn't answer, but he didn't back down either, he stayed where he was.
As the goyim were passing by his house, closings of business deals could be heard being made with Hershke's competitors. Again his wife screamed at him, saying that he lost his mind and he won't have any wares to buy and he won't be able to do business and support the family.
Hershke responded, "The goyim will not get sick if they come to my house, but I might get sick if I go out into the cold." Suddenly they heard the goyim saying, "We will not sign any dotted line before we speak to Hershke." "He died," the competitors lied. "We don't believe you," the goyim said.
With that the goyim knocked on Hershke's window, "Hershke, get up!" He got up, opened the door and let them in. He bought from them everything that he usually bought, without any loss. From then on he never left his house, and the goyim brought him anything he needed for his business, and he made a nice living all his days.
How did Hershke do it? Wasn't his wife right? From a thinking perspective, he wouldn't have been able to hold out; in fact there's doubt whether he would have even taken the Maggid words to heart, had he thought about it too much. Never mind after his wife's nagging. It was the simplicity with which he accepted the Maggid's words, which made it possible for him to maintain his bitachon until the end.
1 Sipurei Chassidim Parshas Bichukosai