"And they brought up an evil report of the land which they had searched unto the children of Israel, saying, The land, through which we have gone to search it, is a land that eateth up the inhabitants thereof; and all the people that we saw in it are men of a great stature. And there we saw the giants, the sons of Anak, which come of the giants: and we were in our own sight as grasshoppers, and so we were in their sight." Numbers 13:32,33
You know God has called you to start a business and it looks like the door is opening, but then you "see" the giants- the monthly expenses of rent, utilities, insurance, supplies, employee wages, etc. How will you pay them? You know God has called you to get an education in a certain field. The door opens to go to college, but then you "see" the giants-- the studying, the tests, Algebra. Am I smart enough? Am I too old to learn it? You know the Lord has promised to restore your marriage or to save your children, but then the giants appear-- you discover he/she is seeing someone else; your child gets arrested. In every promise that awaits there is a giant there too.