When did the prophet Elijah go weak? Not at the moment of challenging the prophets of Baal. Not at the moment when He was praying for the flames of heaven to incinerate his offering and prove His God was the only true god.
He failed when the test was all over. When God was vindicated, the false prophets were revealed, when he was all alone and facing a much smaller trial. He couldn't look back and use the victory to fuel his passion to overcome the next little, tiny trial.
When did Jonah go weak? Yes, at the beginning, then the Lord rebuked and strengthen Jonah for the task He had called him to do. Upon hearing Jonah's preaching about God's judgment, God's mercy and God's forgiveness, the entire city repented. After one of the greatest revivals recorded in the Scriptures, Jonah went outside the city, alone, and pouted over something irrelevant, instead of rejoicing in the salvation of many souls.
These men failed so miserably after a great victory, you almost find yourself wanting to shout, "Do you KNOW what God just worked through you?!?!" How can you NOT remember?"
We're not any different. We can falter after great victory, by not giving the Lord enough glory and using that confidence is His presence to continue to carry us through the next trial.
We can also falter by looking back and focusing on WHAT we were carried through. Sometimes in the looking back, we aren't seeing those Arms of Deliverance, we're seeing the steepness of the trail, the jagged rocks strewn along the path, and the absence of fleshly help along the way.
This is why the Apostle Paul tells us to NOT LOOK BACK! Because we aren't often able to look back and give glory to the Lord. We either give Him too little credit, boasting in our strength, or too little glory, commiserating in our misery.
Instead, Paul tells us to LOOK AHEAD.
Philippians 3:13, "Brethren, I count not myself to have apprehended: but this one thing I do, forgetting those things which are behind, and reaching forth unto those things which are before,
14 I press toward the mark for the prize of the high calling of God in Christ Jesus."
As the family was fleeing their city that was being destroyed in judgment, Lot's wife disobeyed the Lord's instruction to not look back, turned back to look upon her beloved city (or was it her beloved sin?) and turned into a pillar of salt.
We shouldn't look back, unless we are able to give the glory and honor due His Name. We shouldn't look back unless we can use His guidance through our previous path as hope for someone else suffering the same.
When we look ahead and see the prize held in the nail-pierced hands of our Savior, it motivates it, it humbles it, it upholds us.
Another admonition of where to fix our eyes is from the Psalms. We aren't to look back , we are to LOOK UP!
Psalm 121:1,2 " I will lift up my eyes to the hills, from where will my help come? My help comes from the LORD, who made heaven and earth."
Don't LOOK BACK -
LOOK AHEAD to the glory of Heaven at the end of the trail,
And LOOK UP for the help for the rest of the journey.