Sometimes neither the parent nor the child knows when signing up for an activity if it will be enjoyable for the participant. Your son has played soccer for three seasons and does not seem to like it. This is not “giving up.” It is more like, “Well, I gave it a good try.”
There is a difference between quitting a team mid-season and not signing up for the next season. Being part of a team requires doing your workload, encouraging teammates, showing up for practices, etc. You can foster these strong work ethics with many activities in which he can become involved. In other words, finish out the season, but carefully consider signing up again in the future.
No child is going to perform better if the motivation is criticism. Criticism often has the opposite effect. It sounds like your son is not comfortable with this sport. Schoolwork is in his comfort zone. Since physical activity is important, ask him what sport he might like to try. It could be another team sport such as basketball or baseball, or an individual one like cross country or Taekwondo. You and your son will be happier if he is having a good time and is engaging himself in a sport he enjoys.
A friend of mine has three extremely athletic sons who excelled in sports. My friend was often their coach. His fourth son was physically awkward and could not hit a baseball to save his life. After many years of working with him, my friend finally asked his son what it was that really excited him. Robotics was the answer. They have been competing in robotics competitions ever since.
Find out what really excites your son, and embrace his unique talents.