Arch in my back

I have major trouble keeping my back straight during my work outs. No matter how hard i try i arch my back especially durring military presses. Now i have always bin told if you have to arch your back your lifting too much weight . If i lift anything lighter its not a good workout . Whats the deal is it all that bad arching my back ? :lift: :duh: :help:

Sit down on a bench when you do miltary press it helps to stop the back from arching.Normally if you have to arch you back a lot when doing that excercise it means you are lifting more weight than you can handle safely.Wear a belt as well

POSTURE is the key, in normal life try to be conscious of how you are walking and sitting and then it will come in to play in the gym..