The other meraglim had convinced them to see things in a negative light. Conquering the Land of Israel certainly looked difficult. Many things in life appear difficult. Hashem put us in this situation for a reason. See the positive in it.
Great challenges make great people.
Give it your best. A terrible sin, whose effects we still feel to this day. The night of the sin was Tisha B'Av, a night which became earmarked for disasters all throughout Jewish history. Due to the magnitude of the sin, Hashem wanted to wipe out the entire Jewish people except for Moshe Rabbeinu. He would then make a new nation with Moshe as its patriarch.