In Thailand , all 21 - year - old Thai men must partake in a lottery to determine whether they will become military conscripts .
Men have attended at least three years of reserved military training during high school or are considered unfit to serve .
In Thailand , all 21 - year - old Thai men must partake in a lottery to determine whether they will become military conscripts unless they have attended at least three years of reserved military training during high school or are considered unfit to serve .