Why would I fear if it's impossible to fall away? That makes no sense. If we are eternity secure, my fear or lack of fear is irrelevant.
It is kind of a mindblower when you think about it.
But it is clear that if you fear the LORD, you shall not depart from Him (Jeremiah 32:38-40 (kjv)).
And that if you have the fear of the LORD, it is something that will endure for ever (Psalms 19:9 (kjv)).
I think that the key is to take into account those scriptures that tell you that you might fall away and realize that as long as you take them into account, and heed them, you cannot depart from God. And, since no one is able to snatch you out of His hand, that amounts to eternal security, as long as you heed the warnings of the Lord that He has given in His word.
It is kind of like if you were living on a plateau and were blind; and the Lord placed a sound-emitter at the center of the plateau, and told you that as long as you stay in range of the sound, you cannot fall over the edge of the cliff.
There are certain boundaries to walk in; and as long as we walk within those boundaries, we cannot lose our salvation.
Add to this, the fact that if you have been truly born again, you have been sealed by the Holy Spirit and that therefore He is going to motivate you to stay within those boundaries; even to the extent that you cannot violate the boundaries.