The submission of one’s will is really the only uniquely personal thing we have to place on God’s altar. It is a hard doctrine, but it is true. The many other things we give to God, however nice that may be of us, are actually things He has already given us, and He has loaned them to us. But when we begin to submit ourselves by letting our wills be swallowed up in God’s will, then we are really giving something to Him.
Elder Neil A. Maxwell, "Sharing Insights from My Life", BYU Speeches, January 12, 1999
Every one of us has a weakness or, in my case, many weaknesses. We can either give in to them and accept that we are doomed to exist in a limited, progress-less state (which is the case of the Telestial and Terrestrial worlds). Or, we can work to overcome these weakness and forever progress until we reach a state of perfection.
If we really understood the grandeur of the Celestial kingdom, if we really could fathom the peace, the joy, the freedom, the love....something of which we can't even begin to grasp.....then we would do absolutely whatever it takes to get there. Even if that meant sacrificing everything in this life. All our comfort, wealth, status, fame, "weakness", etc., we would gladly give up even for a fraction of what life will be like in the Celestial kingdom.
So, why don't we give this stuff up?
Because, two things; one is that we absolutely need to walk by faith in this life. That is how we grow. That is why we're here in the first place. If we knew what the Celestial kingdom was like, or if we remembered everything from before this earth, we wouldn't grow. It would be easy to choose the right. Opposition would be non-existent. We wouldn't know how to overcome our physical bodies and everything that goes along with that. Progress would be forever halted. Perfection would never be reached.
The second thing is that there is indeed opposition. Opposition trying to influence us and get us to NOT go to the Celestial kingdom to experience that peace, joy, etc. Why does this opposition exist? Because there are those that will never experience that peace, joy, etc., and they want us to fail too. They still want us join them (war goes on still). To be limited like they are. To be imprisoned.
We kept our first estate. Let's work to keep our second too and be together in the highest kingdom.