Depression
Since my late 30s I had occasional bursts over a few days at a time of a sort of nervous exhaustion, which in my mid 40s became more chronic and by the end of my 40s had been diagnosed as a combination of low level anxiety and depression which was by then chronic — meaning that it never went away — and I began to receive a prescription for a small dose of a medication for that which has had to continue ever since. The origins of this are genetic: it is one of a number of forms of mild depression that tend to run in families and can be thought of as a hereditary inability of the brain to keep some of the brain chemical messengers that affect mood at quite the right level for normal happy temperament.
We are told by the literature that a considerable proportion of the population suffer from some form of depressive illness at some time in their lives. Also, there are a number of forms, some of them more severe than others, and typically some of the mild forms never get any worse but also never go away, whereas typically some of the less mild forms do at least recede and go away after treatement (though bouts may last perhaps a year or two even with treatement before they do reccede, and they may come back again, though possibly only many years later).
As I turned 60, I had reached an equilibrium. I had retired, and that was important because the chief thing that could set me off on a descent into a spell of lower spirits would be stress. This could be from work, if I had a time when it was not going well, or perhaps more often some detail connected with work such as commuting to a workplace. As a contractor in the IT business I used to be offered contracts involving working at client premises and when those were any great distance away the daily journeys there and back could, as the years went by, become trying and so stressful. Once I retired from that kind of work, the business of joining the rush hour every morning could stop for ever, and I have generally managed to avoid anything I find stressful.
Historically, I found I could look back to certain times and recognize that I had had a spell of the anxiety-depression in the years before I I had the diagnosis or was put on the medication, and nowadays, I avoid stress in order to avoid triggering any new low. The chief possible source of stress now is probably boredom, and nowadays I give in, perhaps rather too easily by some people's standards, to boredom: I try to avoid spending any length of time on activitiee I find boring, tedious. This means that, for example, I am not very thorough with housework, and in my home the little lumps of fluff collect and roll across the mahogany herringbone-pattern wood block floor like tumbleweed across the desert or the only street of desert towns in areas like rural Arizona (or at least, that is how I imagine it).
I also avoid much travelling. I don't mind a long car drive if I have plenty of time, and if it is important enough to set out in the first place, and if should there be some real catastrophe along the way it will not be another disaster if I get there a little late. I have not done any other travelling except local shopping and visits for several years. I last went away either abroad or on holiday when I visited family in Australia for a few weeks in 2005-6. I don't do holidays; I can't be bothered: there is no point in travelling away on what people call a holiday if the journey, and enduring the facilities (or lack of) and the activities (or lack of) while one is there are more stressful than simply staying at home. So I simply don't take holidays; I probably never will again unless it is to visit family or friends in another country again, let us say one more time before I die, somewhere, some day. Apart from that I cannot imagine myself having the slightest wish to bother ever again. I gues the one exception might be the following: suppose that someone I know were to win tens of millions of pounds on the lottery and then die leaving it to me. Were that extremely improbable thing to happen, so that I suddenly became immensely rich wth no effort, I might consider travelling to a few nice places. I would have chauffeured cars everywhere, stay in 4 or 5 star hotels, only ever go to western Europe, Australia, NZ, the USA, or Canada. I would still never wish ever to go to any other countries in the world under any circumstances. That is certain. And even then I would only really be interesed in bothering if I had friends to visit in a place. Otherwise I am happiest staying at home.