tenacity determination doggedness resolution resolve perseverance grit guts persistence backbone courage resoluteness obstinacy pertinacity firmness nerve steadfastness heart stubbornness spunk purposefulness obduracy intransigence indefatigability application diligence willfulness constancy tenaciousness moxie staunchness assiduity sedulousness tirelessness inflexibility relentlessness patience stickability insistence continuance starch stomach persistency implacability chutzpah inexorableness dedication purpose pluck commitment intentness drive fortitude energy willpower stamina assiduousness boldness earnestness pertinaciousness spiritedness bravery determinedness braveness decisiveness pluckiness endurance decision spirit spine vigour sedulity will vigor granite intension devotion toughness strength industriousness manfulness industry activity rigour intrepidity mettle effort valor assurance indomitability zeal conviction dauntlessness conscientiousness immovability character laboriousness intention design purposiveness