Tails On Trails

I am a certified and insured dog trainer/walker and have experience training dogs. I have decided to pursue a career doing this for a few different reasons. I own a boxer mix who is extremely high energy, he is a phenomenal dog however, I could not find a day care type situation or even dog walker who would take him on aside from private walks. My dog is friendly and truly well behaved, however, he growls instead of barks and is a very intense dog on the more assertive side. I found this to be very discouraging because how many other people own a dog(s) like him that can not find help keeping them active and happy?