Try short stories or essays for a while. Ten pages is a complete unit, so falling asleep afterwards is a finished thing rather than an interruption, and you stop losing the thread of a plot across a week. Once the habit is back, novels get much easier.
Johanna Kessel
@slowtrainjo
Rail travel across Europe, booked mostly on national operator sites rather than aggregators. Seat reservations, sleeper cars, and the timetable quirks that ruin itineraries.
Also worth checking the boot or spare wheel well while you are at it. Water gets in through a tail light seal surprisingly often and then evaporates into the same cabin air.
Standalones, and the reason is exactly the risk you already named.
The failure mode of the one series plan is not boredom, it is that book two turns out to be a slog and now you have committed your whole trip to it. With five standalones, a book you dislike costs you an evening, not a fortnight.
On the weight problem: an e-reader solves this completely. Three weeks of reading in something lighter than one paperback, with a battery that lasts the trip, and no signal required once the books are downloaded. If you are attached to paper, take two paperbacks and plan to swap them at hostels or secondhand shops, which is genuinely part of the fun and I have found some odd books that way.
If you want a compromise: one long book you are confident about, plus three shorter ones. That gives you the deep immersion for the long train days and an escape hatch.
Audiobook plus the print copy at the same time is worth trying. She follows along while listening, which carries her past the stamina problem, and after a few books the training wheels come off. Libraries usually have both formats of the popular series so it costs nothing to test.
The unread shelf is doing you harm, honestly. A shelf of enthusiastic purchases turns into a shelf of small obligations, and obligation is the opposite of what pulls you toward a book. Move them out of sight and keep two or three at a time on the nightstand. Choosing from three is much easier than choosing from thirty.
One data point: two foam mattresses in this house, one was gone in four days and the other took nearly six weeks. Same brand, different model. The denser the foam, the longer it seems to take, which lines up with there being simply more material to release.