Health　behaviour　procrastination　is　closely　associated　with　the　intention　-　behaviour　gap.　However,　research　on　health　behaviour　procrastination　has　tended　to　focus　on　bedtime　procrastination,　with　relatively　few　studies　on　exercise　procrastination.　This　research　examined　the　relationship　between　exercise　procrastination　and　the　intention　-　behaviour　gap　through　three　studies.　Additionally,　based　on　the　temporal-affective　self-regulation　resource　model,　the　moderating　role　of　emotion　as　a　self-regulatory　resource　in　exercise　procrastination　was　explored.　Study　1　validated　the　Chinese　version　of　the　newly　developed　Procrastination　in　Exercise　Scale　in　two　Chinese　adult　samples　(N　=　2376　and　N　=　393).　Study　2　collected　two　waves　of　data　from　447　Chinese　adults　(　M　age　=　31.19)　and　examined　the　mediating　role　of　exercise　procrastination　in　the　intention　-　behaviour　gap.　Using　a　sample　of　453　Chinese　adults　(　M　age　=　20.39),　Study　3　investigated　the　moderating　role　of　positive　and　negative　affect　in　the　association　between　intention　and　exercise　procrastination.　Cross-lagged　analyses　revealed　the　predictive　roles　of　Time　1　intention　on　Time　2　exercise　procrastination　and　Time　1　exercise　procrastination　on　Time　2　physical　activity.　Exercise　procrastination　mediated　the　relationship　between　intention　and　physical　activity.　Examining　the　moderating　role　of　emotion　between　intention　(Time　1)　and　exercise　procrastination　(Time　2),　Study　3　found　that　negative　affect　buffered　this　association.　Findings　highlight　the　role　of　exercise　procrastination　in　explaining　the　intention　-　behaviour　gap　and　shed　new　light　on　physical　activity　interventions,　with　implications　for　promoting　exercise　behaviour.