Whoa Whoa People. They are 9 and 12, let them be kids.
Wait till the kids are older to use weighted balls and all that, they are not physically structured to en dour that stuff yet. Work at different lengths for speed and endurance, keep things simple for them to understand. Try push ups, and sit ups to work core muscles and that will help. But make it fun and not work or you will lose them.
You need to work one day at a time, you start talking about 100,000 pitches before varsity ball you are getting way ahead of yourself. DON'T BURN THEM OUT. Remember this is their life not yours. Make your practice serious but fun and they will want to do it and before you know it you will have 250 with warm-ups done and they will have enjoyed themselves as well.
Wait till the kids are older to use weighted balls and all that, they are not physically structured to en dour that stuff yet. Work at different lengths for speed and endurance, keep things simple for them to understand. Try push ups, and sit ups to work core muscles and that will help. But make it fun and not work or you will lose them.
You need to work one day at a time, you start talking about 100,000 pitches before varsity ball you are getting way ahead of yourself. DON'T BURN THEM OUT. Remember this is their life not yours. Make your practice serious but fun and they will want to do it and before you know it you will have 250 with warm-ups done and they will have enjoyed themselves as well.