welbeck, 30 years experience makes me think that the accepted 'normal' range for thyroxine levels is deceptive! One person I know turns into the Incredible Hulk with levels on the 'a bit on the high side of normal' and is a lovely person who functions really well on the low side. The dosage of thyroxine given by a GP is also heavy-handed, they really have no idea how minute quantities can make such a difference to all aspects of someone's life.
Beau1958 I think there is an age that you feel older around your sixties, and probably that age varies from person to person, but you suddenly realise you don't have the energy you had. And yet, like others have said if you have an interesting full day you don't lack in energy at all, but boy do you know about it the following day! Do as much as you can, rest if you need to, and accept this is nature's way of telling you to relax and enjoy life more. Before retirement age was purely a financial thing, it was set at 60-65 with good reason.