In the beginning stages of training, you may feel a little stiff or sore, and that is okay.
I usually let my clients know that the first few times I train them, I am actually okay with them calling me names the next day as they try to sit down or walk up stairs. If you haven’t worked out in a long time, this feeling may occur for the first few sessions; however, this discomfort should dissipate within a week or two of consistent training. If it doesn’t, it means that myself or another trainer may be pushing you too hard, or you aren’t giving your body enough time to rest.
If you haven’t trained in a while don’t jump into the frying pan by overloading yourself with heavy weights. Start with weights you know aren’t going to be too challenging so you can get a feel for the exercise and learn proper form. Then slowly increase the weight each session until it is challenging.
I will say, however, if you were to take the literal connotation of the word “pain” away, then I will agree that to make gains in your training, you may feel uncomfortable most of the time. Training is hard, and often to see the results that you desire, you are going to have to push your self past your comfort zone.
When your brain tells you that you cannot do any more, do one more. It is this extra one that in time will turn to two, three, and four. This is where you will start to see gains.
However, if you feel a sharp pain or something that just isn’t right, STOP. Don’t push through the exercise.
Tip: Pain is usually sharp; where as, gain is a slow burn.