"Why do people say that this teaching makes them depressed or fearful? I have never had any trouble with it. I just accept it by faith since He is God and, 'His ways are higher than our ways'".

First, you can be thankful that your disposition is one that sees the glass half-full and you can give God the benefit of the doubt so to speak. But the truth is for every person like you who is able to accept it there are probably hundreds who either silently live in terror or who have tried to process this teaching and long ago "fled the building".

Second, the verse you alluded to, used most often in defense of an eternal hell, belongs to a passage (in fact a complete chapter) devoted entirely to the MERCY of God ...not judgment! The sentiment, "His ways are higher than my ways" is directly following one of the most astounding discourses on grace and mercy in the Bible!! It is Isaiah chapter 55:

1 “Come, all you who are thirsty,
come to the waters;
and you who have no money,
come, buy and eat!
Come, buy wine and milk
without money and without cost.

2 Why spend money on what is not bread,
and your labor on what does not satisfy?
Listen, listen to me, and eat what is good,
and you will delight in the richest of fare.

3 Give ear and come to me;
listen, that you may live...

6 Seek the LORD while he may be found;
call on him while he is near.

7 Let the wicked forsake their ways
and the unrighteous their thoughts.
Let them turn to the LORD, and he will have mercy on them,
and to our God, for he will freely pardon.

8 “For my thoughts are not your thoughts,
neither are your ways my ways,”
declares the LORD.

9 “As the heavens are higher than the earth,
so are my ways higher than your ways
and my thoughts than your thoughts.

I will conclude by saying that your ability to not let this doctrine you claim to believe trouble you is not necessarily a virtue. To not think because "His ways are higher" can be evidence of faith or it can be evidence of...not thinking. God says we are to love Him with all our heart, MIND, soul and strength. You have to determine if you are compartmentalizing the truth. Also, how would you explain it to the scores of people who ARE thinking about it and therefore have serious angst and questions about it? If you do any amount of evangelism you will get questions about an eternal hell almost every time. The Bible says to be ready to give an answer for the HOPE that lies within you, not the conundrum you've never thought about.