doggedly, ferociously, relentlessly, fiercely, resolutely, vigorously, valiantly, determinedly, courageously, steadfastly, tirelessly, zealously, stubbornly, bravely, assiduously, obdurately, gallantly, stoutly, patiently, aggressively, energetically, unceasingly, ardently, strenuously, heroically, indefatigably, arduously, gamely, grimly, fearlessly, devotedly, stalwartly, remorselessly, unswervingly, unflinchingly, passionately, fervently, avidly, manfully, mulishly, diligently, ceaselessly, furiously, ruthlessly, vigilantly, obstinately, dauntlessly, intensely, spiritedly, futilely, endlessly, staunchly, grittily, loyally, intensively, nobly, faithfully, unwaveringly, conscientiously, skillfully, fruitlessly, forcefully, hard, implacably, resourcefully, methodically, tightly, insistently, decisively, uncompromisingly, inflexibly, vehemently, vainly, uncomplainingly, feverishly, tenuously, industriously, powerfully, sedulously, selfishly, incisively, vociferously, mightily, eagerly, voraciously, selflessly, rigidly, dogmatically, adroitly, unstintingly, lethargically, jealously, admirably, fanatically, stolidly, traitorously, restlessly, superbly, viciously, daringly, rigorously, possessively

cling, hang, stubborn