Plenty of options:
Just because you don't have a kettlebell or barbell, doesn't mean you have to lose strength. This bodyweight-only strength program can go with you anywhere.
Hard-living types love killing themselves in the glycolytic pathway. But this is far from the only way to achieve good conditioning.
A simple recipe to become more resilient: do moderate dynamic aerobic exercise and avoid overtraining with any type of exercise. And lift.
Run. Shadow box. At intervals you set for yourself. Here and there do pistols and push-ups. No rest and just a couple reps. This is StrongFirst roadwork.
Sure there are tons of other on the website.
I also travel with resistance bands. They are extremely convenient. If you have an achor, with a little bit of imagination and a closed door, you can do lat pull down (to mimic pull ups).
If RB are not an option, Airborne Squat (also called Shrimp Squat) may give you an hybrid between hip / hinge and squat.
OAP / OAOLP are great horizontal push but also great for core (anti extension, anti lateral rotation, anti lateral flexion). Paired with L-Sit (or even HS sit up, they'll secure core training.
Beyond a "plug and play" training, you can also think in terms of movement patterns (squat, hinge, push, pull, core / carry). From there, you can pick up the energy pathway you want to train (A+A, aerobic capacity) and the adaptation you are looking for.
For instance, the 2nd link will work well for "GPP" strength and strength-endurance. The last one would give you cardio vascular endurance while maintaining strength, etc...
Usually, circuits with a relatively high resistance works well for GPP. EMOM also work great.