1, as far as harvest is concerned, if you think you have gained a lot, you can donate more, if you think you have gained a little, you can donate less.
If you want to lose weight, you can go to the valley for free at home and find some free information. If you want to go to the valley to get rid of diseases, I suggest you go to the valley-breaking institution and find a professional tutor to guide you. That's better for you. If the harvest is great, no matter how expensive it is, it is worthwhile.
I wish you success!