I have a $115 per diem.
I use a good chunk of that on "day passes" at random gyms in cities I visit.
Here's my typical day on the road if I land at a humane hour:
1. have already pre-searched my route from airport to hotel, and know which gyms are on the way home, their hours, and if they sell a day pass. Hit the one up I want most
2. on cab ride home, cabbie drops me and my bag (I never check luggage on a trip - you're practically begging an airline to lose your bags, which you don't need when you're working) off at the gym. I leave my bag (locked) with front desk if lockers in the changeroom aren't big enough. Go work out. Buy 5 or so protein shakes at the gym because by then I'm too tired to go grocery shopping. Get to the hotel, do work, and go to sleep
3. next day, work. I have a few bottles of protein shakes I can drink if I starve.
By now, I've usually spent $30 for the gym, another $30 for the protein shakes, and I still have quite a bit of my per diem left over if I get a chance to buy real food.
It's honestly not fun. I don't like traveling for work - I do it because they pay me to do it.
When I run out of protein shakes, and I don't have time to hit a grocery store, I channel my Adonis principles. I save up my $70 I have left after my daily workout. Then, I hit up one nice steakhouse for my once daily meal. Usually a very nice steak, a salad that looks appetizing, 3 glasses of beer, and a dessert. And after, a cigar or some of the local cigarettes (I have to buy those on my own tab, but it's a guilty pleasure when I travel...I like to reward myself with a smoke when I'm traveling)
I'm a creature of habit, and the road is not alluring to me. Some guys, like my old man, loved it and spent 5 days a week traveling for work. I never picked up that gene from him.
I honestly never have trouble going to the gym. I guess I just really like working out, it keeps me sane, and trying out a new gym with new equipment and seeing what the girls in a foreign city look like is plenty enough to get me excited to see a new gym.
Where it gets tough is when you're traveling with your boss, who might be a windbag and wants to talk the whole trip and have non-stop meetings. Or who doesn't understand you'd like a few minutes to workout. In those cases, I have to make due with the hotel gym (this is about 40% of the time for me). Of course, you're lucky to find DB's about 35lbs in hotel gyms, so you do the best you can with what you get. If you look on the bright side, it forces you to change up your workouts a bit...might even be fun. And, you won't be able to lift heavy, so at least you can't hurt yourself in a foreign city! LOL!