My son, Gabriel, is in middle school and my daughter, Vivian, in elementary school.
My ex-husband and I try not to 'push" our children into activities. They choose what they want to do, based on their interest levels and we support them and make sure they do everything their are supposed to do, to make sure they participate to the level they are required to by their teacher. If their interest dies, and they no longer want to do that activity, then we go over the reasons they want to leave, have them give it a second chance for a while, if they're still not interested, we take them out.
For example, Gabriel began an interest in piano when he was 6. He was into it until he was 9, and then he indicated he no longer enjoyed it. We gave him some time to see if it was a passing boredom, but his disinterest contiued, so we pulled him out. He then decided he wanted to take trombone lessons, we enrolled him in that, he's been at it for over a year, and he loves it so much he says he wants to do it forever. He also loves playing football, and does that in addition to trombone lessons and karate lessons. He didn't start in football, however, he started in soccer. He lost interest in soccer and changed after 3 years. He initiates all his interests, we just support him. As you can see, he's a joiner.
Our daughter, however, never got interested in music. We enrolled her in violin lessons when she was 4, but after about a year, she showed she didn't like it. We took her out, and she has never expressed an interest in playing any instrument since. The one thing she does love is gymnastics. When she started that, she wanted to go all the time, and constantly practices no matter where she is. She goes to her lessons twice a week, is advancing well and enjoys it. But she, unlike her brother, sticks to this one interest, and requests nothing more. So she only has one after-school interest while her brother has 3 and both are happy.
Every child is different. Listening, communicating and supporting is key. The main point is, that extra-curricular interests are a learning journey. It should serve as an exercise in showing what's available and a peek into showing your child who they want to become.