When do writers best ideas come?

Writers differ about what they are doing at the time their best ideas come.Some need to be walking along a country road with a stick in their hand before their minds unclench and  inspiration comes.  Others need a stimulant - coffee or alcohol - and others still to be under pressure before they can produce the necessary words. I have found that lane swimming gets me going and I have often worked out plots and found endings for stories as I battle up and down the pool. Admittedly it works best when the pool is  fairly  empty and there is no danger of collision. So easy to forget where you are once you get really going.. Once I practically 'wrote' a one-act play during my three sessions that week in the pool but that is the exception rather than the rule.  Some time ago on Facebook a writer spoke of walking on the tread mill and working on  her novel at the same time. She had somehow rigged up a bracket to hold her laptop but that I feel is taking it to extremes. Too mechanical to my mind. Although undoubtedly there is a connection between getting the blood flowing and the mind producing and if the treadmill, the exercise bike or lane swimming does it for you well and good.  Anything that empowers the muse is worth trying.