If you book a resort hotel from home you'll probably think Goa hotel prices are much higher than you were expecting, but if you book a family-run place once you arrive you'll still find fantastic bargains. It's probably wise to book a few nights online before you get to India, because it can be incredibly confusing at first. After that you might be able to find a similar place for half the price by just checking around the same area.
However, I also happen to be an athlete and about a month ago I reached the point where I had almost no power, no energy, constant hunger (and “hanger”) and cravings for practically anything bad like alcohol, sweets, carbs, artificial sweeteners or energy drinks. I tried to fight it. I started over multiple times. At one point I just couldn’t stick to any sensible dietary routine for longer than a day or two. Intermittent fasting, OMAD (one meal a day), TMAD (two meals a day) and keto all seemed to stop working.
Much of Mexico is ideal in December, after the rainy season has ended; if you go early in the month, you’ll avoid the peak holiday-season rates that kick in around December 18. On the Pacific coast, the landscapes are still ultra-tropical green, and the ocean is bathtub-warm (80s), with exceptional clarity for scuba diving and snorkeling. Mexico City is a smart place to spend the holidays, when the locals have headed to the beach and you’ll find much less traffic in this famously congested city. (Do keep in mind, though, that some of the more sought-after restaurants and galleries will be closed.)
If you’re a bit more on the timid side, you can always use Yelp and TripAdvisor to get good insights on places people have visited. As a disclaimer, some of the ratings may not be accurate on these sites, so make sure you go through and read some of the more recent reviews that people have written. We did this for a few of the places we visited and had no issues.