“Puking is acceptable, blood is acceptable, giving up is not” - seeing slogans like this with more frequency across the Internet concerns me a bit. The underlying message is clear; in light of your true goals, don't let anything deter you, which is a pretty good message in perseverance. Nevertheless, one can't help but acknowledge the unhealthy manner of such messages, and they can unfortunately have the exact opposite effect on readers than intended.
There are an unfortunate amount of people who truly go to extremes in order to standards set by society rather than personal goals. Women are driven to anorexia or bulimia to match the petite models in magazines; meanwhile, not even petite models match the petite models in magazines thanks to the wonders of photo editing software. So this begs the question, what drives you to the point that you feel the need to puke and bleed in your training? Is that the only way to achieve your goals? Is that even the best way to achieve such goals? Here are tips to help you make sure you're staying on a healthy but still high intensity track when you work out.
1. Train hard, but train smart.
There are few better feelings after a workout than the feeling that you surpassed previous limits. Realizing that you can push your strength beyond limits is when you start to learn that we truly have no limits except those we set ourselves. But there is a smart way to push past your limits and test your strength. Running yourself into the ground everyday can force you to pull strength and willpower out of nowhere for workouts, but at the deep expense of your health. You won't get to a 500 lb bench press by going into the gym and trying to bust out 500 reps on your first try because you don't wanna quit. You MIGHT succeed in popping some blood vessels and destroying your tendons though. Be persistent, but be smart; you won't plant the seeds and harvest the fruit in the same day. You'd plant the seeds, but tend to them and ensure that they're taking the steps daily to grow into fruit bearing plants. In the same way, lay the foundation for your training by knowing your goals and reaching hard for them, but take rest times and work at it consistently and intelligently.
2. More flies with honey than sulfuric acid.
If you are concerned for someone else's health or unhealthy habits, how would you help them to change? Granted, if a person's health is damaged because of their lifestyle, then bad habits die hard; it'll take some coercion to break them. So naturally, helping someone to break their bad habits shouldn't be shock therapy, saying “You'll be sweating and bleeding and puking, but you'll be healthier.” That's about as convincing as a Taco Bell ad for the American Heart Association. Don't sugarcoat the need commit to the workouts, because anyone who truly wants to change their physique will need to put in some high intensity dedication to the workouts. But some compromise is necessary to help the person truly commit themselves, and trust that once the person feels the change in their vitality and strength from working out, they'll want to do it more and more. Don't make your incentives sound like you're turning their bodies into a post-apocalyptic wasteland.
Overtraining is real, and it absolutely can happen and come destroy you. Granted, pushing yourself beyond limits isn't necessarily overtraining. Furthermore, people of elite fitness levels can usually take much more training than the average person, so what is essentially cardio for them might be physical torture for someone else. But overtraining absolutely can happen; it wrecks your immune system, and I've known someone to go into hypoglycemic shock from the stress of an incredibly strenuous workout. If this is how you want people to train, then you may need to reevaluate your personal investments as a trainer.
4. For Health AND Strength
As a trainer, as a motivator, you should be advocating for the person's health and strength progress. You may make the person a physical powerhouse and they could be rather proud of the strength they've built, but if that person is subsequently pissing blood and projectile vomiting for the sake of strength, then as a trainer you're neglecting an important aspect of strength training: health. One of the biggest arguments against exercise when it was first popularized was on its detrimental effects to health. We know now that such information isn't true and that exercise is in fact one of the single best ways to develop phenomenal health and energy, but if you're pushing trainees to do the exact opposite of what this training is supposed to do, you'll do more than injure their internal organs and potentially shorten their lifespans. You'll also manage to tarnish the integrity of strength training as a whole. If your own personal goals are so important that your health is of no consequence and puking and blood is acceptable, I'd invite you to think about your priorities, but as an adult you are free to make that decision for yourself. However, as a trainer, your customers come to you in trust and confidence, so imposing this mentality on them is borderline evil. Earn and keep their trust by advising them well.