1. 5'8 is tall for a 12 years old
2. Football is a game of speed strength and mental toughness
3. Basketball is a game of speed mental toughness
In football you have a chance at QB RB WR TE and on defense probably a CB LB SS FS. it deponds on your school height speed and abilities at any of these posistions you have to be fast strong and smart.
And in basketball it really depends on your skill are you a good dribler then be a PG. if your good at Shooting be a SG And your not really tall enough to be C PF S. at least not yet it really depends on your school
And just train like run, jog ... but dont lift weights that can shorten your growth and just study your plays and eat good and thats about it ohh and practice throw catch the football and in basketball drible shoot work on passing the ball!!! Good Luck to youWhat postion should I play in basketball and football?
well you're not done growing so for now in basketball u could go for the SG or PG or maybe SF. Just work on your dribbling skills. Most of the tall football players are receivers and that's a fun position.