Two things that I’ve noticed and that have helped me in similar but not such extreme cases.

1. JOSM is a massive time saver once you learn how to use it. It’s made editing a lot quicker when I’m working on similar tasks.

2. Try break it down into small tasks for yourself. It’s a lot easier to work on smaller pieces of a city/area than trying to cover everything all at once.

Ireland is currently working on something similar (example), I’m not sure how easily you can create your own private tasks for your country/area of mapping.

For this it's best to contact your local group

Check this wiki

https://wiki.openstreetmap.org/wiki/Comparison_of_editors

Rapid AI is fairly good for this kind of stuff.

https://wiki.openstreetmap.org/wiki/Rapid

I would recommend using Mapilio to get street-level imagery for your area that you can then refer back to when mapping bike lanes, streets, etc. You can record from a phone attached to your bike or car.

I'm gonna be giving a bit of contrarian advise here: don't force yourself. No-one asked you to do this all, so take it easy and one bit at a time. If you are a volunteer, just have some fun with it. When you don't feel like continuing anymore, don't.

Another piece of advice: "if you want to go fast, go alone; if you want to go far, go together". (But the latter is more work). If you live in a medium-sized (or bigger) city, maybe there are a few people interested in joining? Post to the local facebook group and do a small gathering with a cup of tea and map together.