One of the hardest things about working out is knowing whether your progression is real or your imagination. Unless you're a fitness expert, it can be very hard to tell whether all your hard work is paying off. That's where a personal trainer can come in - they will design a programme just for you, and by working with you on a regular basis, monitor your progression.
Progression is one of the keys to working out. A good personal trainer will assess you at the start of your programme to establish your baseline fitness, and will then regularly re-assess you in order to measure your progression.
For those who work out alone, it's not so easy to know if your workouts are effective. Many times you see people at the gym who working very hard but getting nowhere. Whether it's because they aren't doing the right exercises, aren't working hard enough, or even some cases, are working out too hard, it is nonetheless true that many people do not get the best from their workouts.
As busy as most people are these days, they will quickly grow tired and quit working out if they feel it's not worthwhile. But by having a professional coach not only design, but also monitor your workouts, you are doing everything possible to maximise the benefits from the time you spend in the gym.
So if you are unsure of how to design an effective programme, or don't know whether you are making great progress or wasting your time, it might be worth considering talking to a personal trainer.