I think if they love it let them do it and encourage them but 3-4 hours sounds horrible for a kid

I played several musical instruments growing up. I was made to play 3 of them but loved playing only 1. The one I loved was a joy to practice and learn. I would practice before and after school to fit in the amount of practice required (some practice was more meaningful than others). But I do always remember having to stay in and practice after school when all I wanted to do was play with friends, so I liked practicing in the morning before school so I didn’t miss out on my friends. I will always remember my mum taking me to see David Helfgott in concert and I was completely inspired by his ability. It made me realise what you can accomplish with the piano. Maybe look into some activities or concerts that use your child’s musical instrument. If they’re just learning classical music, look into some new alternative music that uses their instrument. Mix it up a bit. Make it fun. Let them see what a person can do on their instrument rather than just drills and practice.

I think the key for keeping both children and adults motivated is finding a hobby or interest that they really enjoy. If ur doing something u enjoy then it doesn’t feel like practice when u do it

I need the secret to motivation myself – learning is very important

I think pushing too much can turn even interested kds off.

if your chid is not interested then it is not much point pushing it as they will only resent it later. if their passion is there they will do what is required at their choice.

I think you just have to find your children’s passion! Once you do that, everything else falls into place. When they find something they love, they’ll enjoy doing it and it’s not a struggle getting them to do it

3 or 4 hours a day? I’ve never met anyone practicing so long. Which age are you talking about?
My daughter played recorder since Year 1 and she used to practice 15 minutes a day 5 days a week. She then moved to flute and now it’s now the third year that she plays clarinet. She’s in Year 8. The clarinet teacher expects her to practice 150 minutes a week. She then has half an hour of clarinet lesson at school every week and she plays 3 hours a week in the school band and 1 hour in the symphony orchestra.
She just loves music and I never had to push her to practice. But I admit that the first year (or years) I was always staying with her while she was practicing and that helped her motivation too.

Everyone gets inspired and practices heaps sometimes, and then won’t even look at the instrument between lessons at other times. Don’t force the issue and don’t force music lessons either, if the child truly does not want to play. For mine, joining a band really helped (we still have odd times of zero practice!). Often, if the pieces are not to the child’s liking they simply won’t practice. Good luck!