Israel could look back and remember that day when their ancestors were escaping captivity. They were standing at the banks of a raging river, but an army was pursuing them. They were able to reach safety because the Lord intervened.
Throughout their subsequent history, they needed the help of the Lord and received it.
All of us who have come after Moses can also remember and be grateful. The work of the Lord did not end with Moses, but continued, and continues.
We don't have a promise that our lives will be totally without problems. Rather, we have the assurance that the Lord will sustain us and help us through our troubles.