Not me but my mil. She has an obsession with saving energy and water etc. she does the following:
if she runs tap water to get it hot for dish washing (it’s usually cold / tepid to start), she runs it in to a jug then uses that water for drinking or the kettle;
if she boils in the kettle more water than she needs (by accident), she puts the hot water in a flask to use later;
she turns the shower on to get her body wet, turns it off again to apply shower gel / shampoo then turns the shower back on for a rinse (have asked her not to make teenage dsd do this when she stays);
she doesn’t have a tumble and gets her clothes dry naturally all year round, apparently if the clothes freeze on the line and you knock the ice out then they are dry quickly;
her biggest thing is she eats her dinner at my house a minimum of 3 times a week, at her step daughter’s house once a week and my auntie’s house once a week then tells me how little she spends on food (find this one a little annoying);
she is a lovely woman and a legend at minimising her outgoings. She also goes on holiday most months so she does use her money for fun and I don’t begrudge her.