When I teach people who have major difficulties with this I tell them to start somewhere else rather than piano. Start doing something every day that is not normally included in your routine. An exercise routine is a good idea as it will benefit your physical health and train your mental discipline.
lol, I have a long abiding hatred of exercise and it would require very exceptional circumstances for me to do it in the first place. I'll try to come up with something easier though.
There is no secret about it, enforce a time which you will practice the piano, ideally that is a daily effort but not everyone can manage that but you can build from somewhere. Start with a very small amount, even something ridiculous like 1 minute a day, you can easily build from there at least and determine some kind of increment that suits you.
When I have practiced regularly, I've usually managed an hour a day, but about half of that gets devoted to sight reading for fun. There are at the moment a few minor barriers which have prevented daily practice (i.e. I have to leave my apartment in order to do it, and ask for permission) but those can be overcome through developing a stronger commitment to practicing.
That is a very loaded question which has a very complicated response which needs to be personalized according to your capabilities. Effective practice produces noticeable improvement. You can measure exactly how long something might take you to master rather than it being something that requires an unknown time of brute force repetitions. The most efficient way to work with pieces is to be able to sight read it multiple times and automatically much of it becomes memorized. This usually requires that you work with pieces that is lower than your maximum technical capabilities. Improving the synergy between reading/memorization skills is the way to expand your practice efficiency.
Repetitions need to be mindful and always done in a controlled manner. That may require that you drop notes and slowly add them, or alter other parts of the music and slowly build towards the final product. It may use slower tempo controls, controlled pausing between particular patterns, writing out logical statements which allow you to understand a group of notes, observing small changes between groups, the technique found in the fingering and patterns in the fingering themselves, how to play slow but preserve fast movements, so on etc etc etc.
I'm not entirely sure how to apply this to my current situation but appreciate the advice—this does give me more to think about for the next time I practice.
Efficient practice allows you to get through work without worry about the time spent. This is because you are constantly aware of improvement while you are practicing and this grabs your attention. It no longer is merely a mind numbing repeition over and over again hoping that eventually the procedure becomes easier, it may eventually work but it is just masochistic. There is also a danger that you are simply repeating in an incorrect manner so are simply lost in the techincal wilderness.
Yes, I've never noticed any improvement while practicing—it usually feels like I get worse over time, because my hands get tired, or the keyboard becomes slippery due to sweat, etc. But I also do set pretty high expectations for myself.
Learn smaller works, not completing something you begin is a very bad habit to fall into and needs to be squashed.
My experience has been that although I might memorise a piece or learn it to a certain level, eventually I get stuck somewhere that I don't see improvements from repetition (e.g. can't get the Arietta of Op. 111 to be quiet enough, or can't play the fast running passages in the left hand in the last movement of Mozart's K 576, or can't play the staccatos in Mendelssohn's Op. 67 no. 2 softly enough, etc) and give up.
You are biting off more than you can chew. It is no wonder you feel so stressed out. Why are you submitting yourself to such large scale pieces?
The thing is I don't think of 109 as a "large scale piece" (it's about 20 minutes when I play it) and it only has four or five passages that are very difficult for me. I felt it would be an easier piece that once I'd learned it I would then be able to move on to Op. 110, 111, 106 and 120, the latter two of which are genuinely large scale pieces at 35 & 55 minutes respectively, as well as technically much more challenging.
There is no need for this and you really should invest your time in smaller scale projects. You need to have a list of completed works which you can control with some mastery, it is no good simply thinking everything you learn is "recreating the technique wheel" and a huge grind to complete. Build your skills and you will have the tools to cut through harder works much easier.
I mean, that is fair, but most of the shorter pieces I'd like to play are just as difficult or more so. For example I find more difficult passages in Ravel's Alborada del gracioso (duration 6-7 minutes) than I do in Beethoven's Op. 109, and expect to end up spending a lot more time working on it. I can't think of a lot of genuinely easy pieces that are nonetheless musically interesting enough for me to want to learn them. (The few I've considered: C Schumann Notturno op. 6 no. 2, F Chopin Mazurka op. 41 no. 1 [in c# minor], Scarlatti K 296 [though at 11-12 minutes, not that short], Janáček In the Mists [also not that short], Brahms Op. 117... basically all music on the slow and quiet side lol)
Thank you though, I'll keep thinking about this