Don't try to stop it... the more u try... the more "it" want to think
Just like it flow like a river...
U can try to do some visualization like spiritalk said before... but as for me... visualization not really suit on me
meditation has so many form... pick the one that suit on you
by practice it every day... u'll learn which one is suitable for you and which one are not
like me... i always meditate in a very busy and crowded parking lot every morning...
i can focus well while so many person can't... but i can't do meditation in a silent place
so every person has their own unique form

Mantara means the time you did learn mantra and were not way keep the flowing meditation by calming the mind without thought and allowing the energy with a quiet mind without thought apparent and begin relaxing the mind by easing all thought and begin a mantra without the thought s the mind hears and keeps the electrical valu beta and a gam~m0 wave not allowing the mind to aum settle while you have all the~@ thoughts moving around in your mind (at the head). Mantara itself will be a relax and breath new technique showing when you did learn a mind quiet mantra you may remind the meditation affect energy (what I call chai) and @ include breathing with the way mantara will help begin medita tion and then remind the mind quiet by sensing all thought when yer mind was active it was not meditation.. when your mind was quiet and your thoughts subside and begin the mind 0m upon ways u hearing may begin the senses and enlighten the inner spirit with quiet peace and thoughtless accord with Nature. Aum PotMi 0m~^

Remind yourself meditation was not with activon thoughts.. it will be with thoughtless balance and the way begin mantara will be a remind meditation you began with and allow breathing and peace (and quiet) until you be gin sending the thoughts away with calm remind about your new ideal not force thoughts out let them quiet with a remind about mantra exampl Ayur~Veda aum OK Amen.