I've been playing my grandkids for a few years now. The older ones (about the same ages as yours) are completely different. The younger one is a mama's boy and the older one is the black sheep. Pretty much all of the kids get a break from me, but they rarely win. If they do, they earned it by making a tough shot or running out 2-3 balls. The lesser skilled get two turns at the table for each of mine. My sons are both very competitive and won't let me take it easy on them. My oldest grandson gets more breaks because he is a better sport and his parents don't treat him very well. The next one gloats if he wins, so he rarely if ever gets to win. He will pout and walk away if he loses too much, so I'll string him along for awhile if I'm in a good mood. He acts like I'm obligated to let him win because of my superior skill. I don't think that's a good thing to teach him, so I'm actually kind of rough on him sometimes. He has it pretty easy, though, so his hard knock lessons don't weigh on him for very long. The 3rd grandson gets everything he wants and is very spoiled by his mom. I've actually seen him get tired/bored of opening Christmas presents. He gets very few breaks from me. He has his own table now, so I have to keep on my toes with him. I congratulate him when he makes a good shot, but he really has to do well to get my praise. He also gets corrected when he gloats or exhibits poor sportsmanship.
The last one is going to be the toughest. He loves to play, but doesn't have any discipline. Half his time is drills and the other half is play. I let him have two turns also. He just runs up and one strokes most of his shots. He's more focused on hitting balls than making them and it will take a long time to break this habit. Half the time he's not even shooting at a makable shot. I would have to reprimand him on every shot to get him to change. (It took three sessions with me reminding him on almost every shot to get him to stop moving his bridge hand up in the air as he made his final stroke.) I'm hoping that he will grow into wanting to do well as the rest of his life changes. We had to take him and his sister away from his mother as she wasn't being a parent. They both start crying whenever they have to think or try to solve a problem and have never had to do schoolwork, homework, or chores. He likes the structure of doing the drills and having to make 3 or 4 in a row before moving on to the next one, but sometimes gets too bored to finish. I think he'll eventually come around. It just won't be easy.
Above all, I am thankful for the time I get to spend playing with all of the grandkids and want to make it a fun, learning environment for them. Letting up on them so they can get more shots in and even allowing them to win once in a while gives me more opportunities to observe how they react to different situations so that I can help guide them in the right direction. Remember that teaching them how to talk smack without upsetting the other person is a valuable lesson, as is knowing how to tell when you have upset the other person.
The last one is going to be the toughest. He loves to play, but doesn't have any discipline. Half his time is drills and the other half is play. I let him have two turns also. He just runs up and one strokes most of his shots. He's more focused on hitting balls than making them and it will take a long time to break this habit. Half the time he's not even shooting at a makable shot. I would have to reprimand him on every shot to get him to change. (It took three sessions with me reminding him on almost every shot to get him to stop moving his bridge hand up in the air as he made his final stroke.) I'm hoping that he will grow into wanting to do well as the rest of his life changes. We had to take him and his sister away from his mother as she wasn't being a parent. They both start crying whenever they have to think or try to solve a problem and have never had to do schoolwork, homework, or chores. He likes the structure of doing the drills and having to make 3 or 4 in a row before moving on to the next one, but sometimes gets too bored to finish. I think he'll eventually come around. It just won't be easy.
Above all, I am thankful for the time I get to spend playing with all of the grandkids and want to make it a fun, learning environment for them. Letting up on them so they can get more shots in and even allowing them to win once in a while gives me more opportunities to observe how they react to different situations so that I can help guide them in the right direction. Remember that teaching them how to talk smack without upsetting the other person is a valuable lesson, as is knowing how to tell when you have upset the other person.