You're not alone in the struggle to stay healthy and keep going. I've been fighting this for the past few years. I'll be really good about going to the gym or doing something active every day for a few months then something will happen. Have had to take time off due to a number of injuries (sprained ankle with torn ligaments, knee/IT band issues, torn shoulder labrum), but I also struggle to get back into my routine after going on vacation or taking a few days off because I'm busy. You described this struggle perfectly - it's draining. I do so well and see tons of progress then undo that all over 2-3 weeks when I'm laid up and end up eating like shit. I feel like I'm beginning to get better at overcoming this cycle though. Recognizing when I'm falling back into bad habits and making changes to get back into a routine. Routine is the key to it all, for me at least. I don't normally work out with other people so I need things to keep myself accountable, such as going to the gym before work so it's a part of my daily routine.