Find a crate he'll fit in, and find a good obedience class and take him.
Obedience classes are not just for the dog, they are for the owner as well.
Be more active in your exercise of him. If mine got walked twice a day, she'd be bouncing off the walls from boredom. Boredom = trouble = chewing stuff up.
Danger Danger vom Kleinen Hain aka Masi
"Angel" Jakoda's Bewitchen Sami CD OA OAJ OAC NGC OJC RS-O GS-N JS-O TT HIC CGC
"Angel" Steinwald's Four x Four CGC HIC TT
Harmonyhill's Hy Jynx NA NAJ NAC NJC RS-N JS-N HIC
"Angel" Jakoda's Jagged Edge