What do you think are the advantages and disadvantages of working out in a gym without a personal trainer?

Hire a personal trainer and you will make rapid progress. Not only will he teach you training methods, but he will also give you a training plan and diet plan. It can also protect you while practicing and reduce the chance of injury. If you don’t hire a coach, unless you have strong self-awareness. If you are very passionate about fitness, you will only spend your passion on the wrong movements, and then you will often get injured, and your fitness journey will end here. Even if you are very careful not to get hurt, if you fumble bit by bit and ask others for advice, it will take a long time to get started, and progress will be very slow. If you don't have a strong interest in fitness, it will be difficult to stick to it.