Thomas Paine wrote this in order to encourage the Revolutionary War soldier.  Early in the war, the colonial army was faring quite poorly with military defeat and few supplies.  It did not help that the army was facing the world's main superpower at the time, Great Britain.  Paine wrote these words to everyone in colonial America, reminding them that there would be struggle.  Soldier and civilian alike would suffer in this war; however, by struggle, the American citizen would value his independence and would do anything to hold on to it.  Paine hoped that this experiment in self-government (a novel concept at the time) had a chance to remain viable if people remembered what it took to keep it.  By fighting bloody battles and undergoing drastic hardships, these Americans could remind Americans later of what it took to create their government and this would be valued more than if Britain just gave it to the Americans.