Dezi loves the sunshine out doors! His first few times, he was very scared, but on my lap, he learned to enjoy it. I First got him used to his harness and leash, which I always use when he is outdoors, on the chance that he would get spooked, and bolt.
He is too big for the store bought harnesses, so I made one for him, using the hardware from a store bought one. It is more comfortable, and especially designed to accommodate his magnificent beard. The first harness was a disaster. He spooked, inflated his beard, and the harness choked him. Suddenly, I had a terrified Dezi thrashing about and turning black! I couldnt get it off him fast enough, ended up cutting it off him. I felt like a bad owner. But, he settled down, and we tried a better design, home made, and it worked just great.
At four months, Beardies are still a bit skittish (they settle down considerably around six months old)...but if you have had him all this time, he has bonded with you, and if you have been handling him so that he has complete trust in you keeping him safe, then he should be okay out on your lap. Let him get completely accustomed to the outdoors while on your lap, before even attempting letting him go freely, and always have him on leash for safety. To get him used to the harness and leash, let him wear them around the house several times, before going outside.
Oh! And always touch any surface, before placing him on it...sidewalks can get very hot, and burn his tender underbelly.
Dezi demonstrates his harness and leash, while outside on my lap...he loves the sunshine!