difficult, tough, daunting, tricky, rewarding, stressful, arduous, perilous, turbulent, grueling, problematic, frustrating, dicey, gratifying, complicated, treacherous, exciting, competitive, satisfying, successful, unpredictable, perplexing, uncertain, resilient, inhospitable, interesting, demanding, problematical, roughest, bumpy, troublesome, rockiest, onerous, strenuous, hectic, rough sledding, vexing, eventful, volatile, exhausting, important, contentious, doable, inspiring, compelling, intimidating, obstacles, tortuous, appealing, precarious, formidable, advantageous, complex, favorable, impossible, tumultuous, unforgiving, changing, troubling, confident, harder, supportive, invigorating, strong, undoable, unchartered, dangerous, confusing, motivating, optimistic, untenable, exasperating, exhilarating, busy, robust, unsettled, profitable, humbling, constrained, litigious, evolving, facing, headwind, harsh, adaptable, operationally, thorny, difficulties, hostile, mettle, rigorous, adapting, aggressive, exceptional, uphill, sticky wicket, confounding, diverse, realistic, critical, dynamic, adversity, unrewarding, nonthreatening, noncontroversial, ticklish, taxing, trickier, controversial, easiest

afield, commonplace, drop out, humdrum, prosaic, spoonfeed, steer, unglamorous, unglamourous

ambitious, difficult, hard, intriguing, provocative, stimulating, thought-provoking