You don't live with a constant bad feeling. You only experience the bad feeling when there are temptations to distrust God's promises. And even then, you use the bad feeling of fear to send you running into the safe yard of God's goodness and promises. So normal Christian life is aware of the fearful danger of unbelief, but does not live paralyzed or terrorized by it. It lives in faith.
Fear only rises where faith starts to weaken.
And it only rises long enough to get us back into the peaceful fearlessness of faith. Now there is one more thing I want to do with this text. Verses 3-10 are written to support the main point which we have looked at in verses 1 and 11, namely, be diligent to enter God's rest and fear lest you fail to enter it because of unbelief. Verses 3-10 are written to show that this promise is really there in the Old Testament. The text is very complicated, so let me just sketch a very brief outline for you.