endurance – n. the ability to do something difficult for a long time : the ability to deal with pain or suffering that continues for a long time

stamina – n. great physical or mental strength that allows you to continue doing something for a long time

pace – v. to control or set the speed of (someone or something)

long haul – n. a long distance: a considerable period of time

lose steam idiom : to lose strength, force, or energy : to slow down

bored – adj. filled with or characterized by boredom

burnout – n. the condition of someone who has become very physically and emotionally tired after doing a difficult job for a long time