If you like drinking tea and make a whole pot, then get a tea cosy. Or even better, get your sister to make you one (thank you sister!). It will keep the tea warm for about an hour and half so you can keep enjoying it. If possible, you should take out the strainer or tea bags after 5 minutes or so because otherwise it will keep brewing.
You could even get a plunger teapot if you really want to do things properly!