On any given day, I have something fun to do.Yet while time is retirement's great gift, it can become a curse for anyone who has devoted decades to a career (whether that job is loved or loathed) and then suddenly wakes up with relevance deprivation syndrome and no firm plan on what comes next.It's all too easy to make the mistake of equating inactivity to indolence — the feeling that if you're not doing something constructive with your time, you're wasting your life.You have to kick that protestant work ethic to the kerb.I've come to realise it's OK to have days where you simply read a book or go for a walk and watch a documentary on Netflix.I think a lot of fear about retiring comes back to whether living the life of leisure is actually something you can afford.A survey of 1,017 Australians last year by financial comparison website Finder revealed one in five — the equivalent of 4.3 million people — believe they don't have enough money in their super or other investments to get by in retirement.The Association of Superannuation Funds of Australia's (ASFA) latest estimate is that single people need at least $630,000 and couples at least $730,000 for a comfortable retirement at age 67.ASFA says this equates to $54,840 a year for a single person and $77,375 for a couple Which means I should have at least another 20 years of leisure time.I have things on my list I might not get around to for a while