oddly I do feel satisfied when I’ve unblocked a tough drain
I do like wiring and solving a fault
Looking at those (I'm no psychologist or career adviser), they are both worlds apart but similar in that they are short work, fairly challenging and people really appreciate the results. You also feel a lot of satisfaction from a positive conclusion to that type of work which will raise your self esteem. With the drain work, you are exercising your body, breathing deeper and the blood is pumping. That has a positive effect on the mind,
read this link.
Have you thought at length about the work you enjoy?
Make a list of the things you get an equal amount of job satisfaction and remuneration from.
It can sometimes be that you are in the right trade but not doing the right work for you. Plumbing is a vast subject as you know! (people do not appreciate the amount of knowledge inside a Plumbers huge Brain).
If you can gear the work that pays equally in both the things I mentioned, you will tend to be happier at work.
@YorkshireDave mentioned the 'type' of people he likes or prefers to work for. That has a massive effect on your happiness too. If people appreciate you, you 'aim' to please them and that in turn leads to satisfaction. All this goes around in circles. If we provide and people appreciate, we feel good about what we provided. This side of things is nothing to do with money. However, getting paid as well as the two way satisfaction is a major bonus.
Maybe you would be suited to self employment?
It is long hours, hard work, stressful etc. but in my opinion it pays in more than just money. The customers are yours and if you look after them, they will look after you. This gives a sense of loyalty, responsibility, job satisfaction and so on. It provides you with 'a way of life' rather than 'a job', or that's how I see it. It provides you with more freedom too. The loyalty and responsibility you feel toward customers and the business ensures that you keep working (if it suits your personality) but 'knowing' that the freedom to choose the work you take on and when you do it (to a certain extent) has some positive psychological benefit to my mind.
Hope this helps!!