text: You will not blow it.  Work out by lifting anything with weight with your arms and pushing things with your legs.  Do some pull-ups and sit-ups to get your whole body conditioned.  Run lots too.  That will improve your quickness to rush the passer.  And always take care of your body.  Get your motivation and self-esteem up.  You can be a great lineman.  Just believe you can make that play.  As a defensive lineman, you probably won't blow it on a missed tackle.  It will be something stupid like a facemask that could cost your team and you sound like a smart enough guy to avoid that type of humiliation.  Try these workouts and know you will do well in your tryouts and good luck in the up coming season.