on a treadmill

constant continual continuous endless incessant nonstop perpetual unceasing unending unremitting

amaranthine day-and-night eternal everlasting indefatigable interminable perennial round-the-clock uninterrupted untiring world-without-end

broken ceasing completed discontinuous ending finished halting inconstant intermittent interrupted stopping temporary terminable terminating transient

concluded infrequent irregular occasional

continued endless extended regular repeated stable steady unbroken unceasing uninterrupted

connected consecutive day-and-night everlasting interminable looped no end of no end to perpetual prolonged timeless undivided unfaltering

broken discontinuous imbalanced intermittent unfixed unstable unsteady wobbly

ceasing completed ending finished halting interrupted sporadic stopping

fruitless hollow impractical ineffective ineffectual insufficient trivial unproductive unprofitable unsuccessful useless vain worthless

abortive barren bootless delusive empty exhausted forlorn idle impracticable in vain no dice nugatory otiose out the window profitless resultless save one's breath sterile to no avail to no effect to no purpose trifling unavailing unimportant unneeded unreal unsatisfactory unsubstantial valueless

effective fruitful helpful productive profitable successful useful valuable worthwhile

hopeful

boundless continuous endless eternal incessant limitless long-winded never-ending perpetual protracted

boring ceaseless constant day-and-night dragged out dull everlasting immeasurable interminate long long-drawn-out looped no end of no end to permanent spun out strung-out timeless unbound unceasing uninterrupted unlimited wearisome

brief ceasing ending ephemeral halting intermittent interrupted limited stopping temporary terminable transient

bounded finite

barren empty exhausted fruitless idle impractical in vain ineffective ineffectual save one's breath to no avail to no effect to no purpose trifling trivial unproductive unprofitable unsuccessful useless vain valueless worthless

frivolous fruitless petty trivial

abortive barren bootless delusive delusory empty going nowhere hollow idle in vicious circle inefficacious insignificant misleading no-win not a prayer nugatory otiose paltry pointless profitless puny senseless shuck slight sterile time-wasting trifling unavailing unimportant unnotable unproductive unprofitable valueless void worthless

consequential important significant useful

modest possible shy