I have tried several different tacks. I am not a runner. I use weights, cycle and elliptical at home. I always pack workout clothes. If I have to stay in a hotel I look for a one with a gym or at least an exercise room. Some are quite good, others minimal or not in good condition. Best I've been in, Dallas, had a full weight room, several aerobics machines and a nice pool. The worst advertised a gym room and had a clapped out Universal machine with not much else. Driving, I used to pack a couple of 1" dumbbell handles and about 30# of plates. They fit in a small molded plastic, flat equipment case. That got old. I discovered exercise tubing. Tubing is available in different tension ratings. I got mine at Walmart. Everlast has a $20 kit of three tubes and two handles so tubes can be doubled or tripled to vary tensions. A short tube and a long tube and a jump rope will allow you to just about simulate a normal gym workout with less than a half pound of equipment and next to no luggage space. Add some bodyweight exercises, stretches and you can do 45 minutes in your room or wherever. Great for a cold, rainy day when you might not want to run. There are tubing workouts online. Use a hassock for a bench if available. In hotels, at least spread a guest towel on the floor. Run stairs for aerobics and warm-up.