The routine has to be for something
Sagittarius Sun, 6th house: you can do repetitive work indefinitely if you believe in what it is for, and you cannot do it for a fortnight if you do not. Meaning is the fuel rather than a bonus. You need to be able to state, in a sentence, what the daily grind is serving.
That makes you unusually resilient in demanding jobs with a purpose and unusually poor at comfortable ones without. It is worth knowing which of the two you are currently in, because the tiredness feels identical and the remedy is opposite.
The job keeps growing under you
You take on more because the new part looks interesting, and the role expands until it no longer fits in the hours. Nobody imposed this. Before accepting the next addition, name what comes off the list, out loud, to whoever is asking. The answer is often that nothing does, which is itself useful information.
Movement is not optional here
A working life conducted entirely at a desk affects you faster than most: the mood goes first, then the sleep. Your body is built for distance rather than for stillness. Put walking into the working day itself rather than saving exercise for the evening, because the evening version is the one that gets cancelled.
Week five is where you disappear
Any new responsibility is fascinating for about a month, competent for another two, and then quietly abandoned in favour of something newer. Colleagues learn this about you before you do. Choose two responsibilities you will see through regardless of how interesting they remain, tell a colleague which two they are, and let the churn happen everywhere else without guilt.
You improve things by being cheerful about them
Your effect on a working environment is real and underrated: difficult stretches become bearable, people stop catastrophising, and the atmosphere lifts because you genuinely believe it will be fine. That is worth as much as any technical contribution. Just check occasionally that optimism is not being used to avoid a problem that needs stating plainly.
Say what the work is for
Your engagement depends on purpose more than on conditions, so the most useful question at any interview is what the organisation is actually trying to do. Ask it directly. A well-paid role you cannot answer that question about will lose you within eighteen months, and the resignation will surprise everybody but you.
Distance, not intensity
Your body responds to long steady movement rather than to short hard sessions, and the hips and thighs are where stiffness collects first. Build the week around something that covers actual ground: walking, cycling, swimming, anything with distance in it. Frequency matters more than effort here, and being outdoors matters more than either of them.
You lift the shift
Colleagues enjoy working with you because you make the day feel less like an obligation, and that is a contribution nobody records. It also means people bring you their gloom to be lightened. Once in a while say that you are having a bad week yourself, and let somebody return the favour.
Freedom bought with the boring job
A tolerable role that funds the life you want is a legitimate strategy for you, provided you actually spend the money on the life rather than accumulating it. Name what the job is buying and put a date on it. Without the date, the arrangement quietly becomes permanent and stops being a strategy.
Staying past the interesting part
Competence here is built by remaining with something after the novelty ends, which is the exact point at which you reach for the next thing. That is the whole discipline. Choose one commitment and pass through three of those moments deliberately; what is on the other side is a skill you currently do not have.