The process of apprehending a promise gives you the strength to abide in its benefits.
God's promises set us up for certain victory. He declares a word of promise fully convinced that you will lay hold of what he has spoken. And when you do, the riches contained in that promise are all yours.
If you leave it lay, it will not be because it was too difficult to obtain, only that you were unwilling.
God only gives promises he knows you can believe and enter. Otherwise, what's the point?