When it comes to your workouts:
Solution A: See if your gym has a multi-city membership option so that you always have some equipment nearby.
Solution B: If you're in charge of picking the hotel, opt for one that has a gym. Even if it hasn't been renovated since the 80s, weights are weights and regardless of if they're pretty, they'll give you results.
Solution C: Visit a new gym. Sure if may cost you a drop-in fee, but its always cool to try out new places and new equipment. In my experiences, especially independent gyms, are always excited to host someone new to the city and maybe even give you a free pass for a one-time workout!
Solution D: Master the art of a hotel room workout. No equipment? No problem. Go for bodyweight endurance circuits to get your heart pumping (see below).
Solution E: Run outside. You were given 2 feet and a heart beat for a reason ! Even if you're not normally a runner, its a good change up from your routine. Even if you've never been a runner, there's no better time to start! You can also try walking/jogging intervals (see below).
When it comes to your nutrition:
Solution A: if possible, prep your meals and bring them with you. Most modern-day hotels come with a mini fridge, and even if your room doesn't have a microwave, most hotels will give you access to one.
Solution B: If you can't bring your meals, and have to eat out, make yourself a meal plan that you can stick to at restaurants and/or cafes.
Solution C: Choosing healthier places to eat is obvious, and way easier said that done. So instead, look up new restaurants/cafes in the area beforehand, know which ones cater to healthier eating, and make a reservation. That way you have a new restaurant to look forward to, are more likely to eat healthy and have accountability to go there rather than skip out and pick up a cheeseburger on the way back to your hotel.
Solution D: Tell your coworkers/friends whats up. Other people are more willing to help you if they know your backstory. Your friends will understand your refusal of a poutine food truck if they know you "have 4 pounds left to lose before your best friends wedding in a month" rather than thinking you're just being a picky-eater with the "watching what you eat" excuse
If all else fails, and all the odds are against you, and there was nothing you could do while you were away and all the gyms in the area had been burnt to the ground by anti-fitness dragons...don't sweat it - at least not while you're away.
Instead, sweat it out with an extra workout per week the week before you go and the week after you get back. That way you can stay on track with your fitness plan and not feel totally guilty while away.
Otherwise, here are some on-the-go workouts you can try from the comfort of your hotel room, on the treadmill in a gym, or outside while exploring the new city you're visiting: