stamina

endurance, staying power, tirelessness

beans, bounce, brio, chutzpah, dash, drive, dynamism, energy, esprit, gas, get-up-and-go, ginger, go, gusto, hardihood, juice, life, moxie, oomph, pep, punch, sap, snap, starch, verve, vigor, vim, vinegar, vitality, zing, zip

main, mettle, might, muscle, potency, power, puissance, strength

determination, perseverance, resolution

brawniness, fitness, hardiness, huskiness, sturdiness, virility

health, healthiness, soundness, verdure, wellness

backbone, fiber, fortitude, grit, gumption, pluck, pluckiness, spunk, temper

courage, courageousness, guts, gutsiness, heart, intestinal fortitude, nerve