Simple, walk everywhere! Go on hikes to get great views, walk through the towns or countryside — whenever you can, opt to walk instead of taking the shuttle across the resort or the tram across town. You get to experience the location and immerse yourself in the culture so much more this way in addition to keeping active! And if swimming, canoeing, kayaking or snorkelling/diving is an option, go for it!
An idea would be to get up one hour before anyone else does or one hour before you would usually do so you can fit a little but intense routine. Keep your mind on your goal!