On my last trip aboard (to Portugal), I found myself once again doing 3 things I hate myself for doing:

1. Watching TV, particularly if it's a movie or TV show I would never watch at home. Add in ad breaks in a language I couldn't understand, and I might aswell as just slept in instead.

2. Going to Irish pubs. I don't go for the 'craic' or to see if I can make new friends, but I do go because there's a better than average chance that they'll have my favourite tipple. Even if that tipple is twice the price of all other beer and been on the shelf since it was purchased by the bar in 1987. I have managed to reduce this to an occasional 'treat' and will seek out local bars as much as possible.

3. Going to the same restaurant. This is one I'm actively discouraging myself from doing, but if there's a nice restaurant near your hotel, and you're back in your room at 8 at night and hungry after a day of hiking/sightseeing/sitting by the pool, it's so difficult for me not to just keep going back. I make it slightly more exciting by having a different dish each time, which might be just enough :P