Similar word to unenergetic:

apathetic, asleep on the job, careless, comatose, dallying, dilatory, drowsy, dull, flagging, idle, inattentive, indifferent, indolent, inert, lackadaisical, laggard, lagging, languid, languorous, lethargic, lifeless, loafing, neglectful, out of it, passive, procrastinating, remiss, shiftless, slack, sleepy, slothful, slow, slow-moving, snoozy, somnolent, supine, tardy, tired, torpid, trifling, unconcerned, unenergetic, unindustrious, unpersevering, unready, weary