I make sure I go play 3-4 hours of Tennis on Friday evenings as there is not much productive stuff to do, and try not to work on Saturdays, playing more tennis or spending time with kids and going out dining with family. This recharges me for starting work again on Sunday and then its non-stop till Friday evening. I've also felt that tackling challenges one at a time helps, and not worrying seeing the top of Mount Everest thinking how will I ever get there. Smaller milestones and incremental development, slowly but steadily has worked out so far from Idea to Product Launch to Patent Granted and now raising funds and ramping users.