Some days are unbearable. Some days it takes all the strength we have to trust in the Lord. There are sayings we use to get us through sometimes: "One day at a time", "that which doesn't kill us makes us stronger", "this too shall pass" and so on. I actually prefer this verse.
When we trust in the Lord, we have all we need. He IS our strength. He provides us with the determination to move forward. He provides us with the courage to do what others have not. He provides us with the companionship of others. He allows us to stumble and fall but fails to leave us there. He allows us to be forgiven. He gives us eternal life.
On the good days, it's easy to praise the Lord! It those days that try our patience, break our hearts and push us beyond our human limits that we need to remember to trust Him - He IS our everlasting strength!!!