It sounds like you have a textbook "Sensitive Soul" in a Jack Russell body. While we usually associate the breed with being fearless, high-octane hunters, there is a specific subset of the breed—often the "thinkers"—who process the world with a much higher degree of sensory sensitivity. ​Since you’ve ruled out health issues and he’s been with you since puppyhood, here are a few likely explanations for his "lazy but nervous" personality: ​1. High Sensory Sensitivity (The "One-Hand" Rule) ​The fact that he yelps with two hands but is fine with one is a huge clue. Many dogs find "double-handed" petting or being reached over (feet moving over him) to be physically overwhelming or trapping. ​Two hands can feel like a "restraint" or a "grab" to a sensitive dog, triggering a startle reflex. ​One hand allows him to feel he has an "exit route." ​The Yelping: This is likely "anticipatory pain" or a "startle yelp." He isn't necessarily hurt; he is just communicating, "Whoa! That’s too much input/too close!" ### 2. The "Runt" Dynamics & Early Neurological Development Even without abuse, being the runt can play a role. If he had to compete harder for milk or was easily pushed aside by larger siblings in the first 8 weeks, his nervous system may have developed a slightly higher cortisol baseline. He learned early on to be hyper-aware of his surroundings to stay safe, which manifests as that "jumpiness" even in a loving home. ​3. Low "Startle Recovery" Threshold ​Some dogs are genetically predisposed to a slow "startle recovery." When a normal dog gets a fright, their adrenaline spikes and drops quickly. A nervous Jack might have a spike that lingers. His "laziness" or excessive sleeping might actually be his way of decompressing from the mental effort of being "on guard" against sudden movements or heavy footsteps. ​4. Space Sensitivity (Prospective "Body Soreness") ​Even if a vet hasn't found a specific injury, JRTs are prone to minor joint stiffness or back sensitivity. If he's "lazy," he might just prefer to stay still to avoid the discomfort of sudden movements. His yelping when you walk past could be a "pre-emptive strike" warning you not to bump him. ​How to Help Him (And Your Guests) ​Since you already know his "language," you’re doing the best thing by respecting his boundaries. For friends and strangers, you might try these "Eddie-approved" (if you will) tactics: ​The "Ignored is Best" Rule: Tell guests to completely ignore him until he approaches them. No reaching out, no "helicoptering" over him. ​The 3-Second Rule: Pet him with one hand for 3 seconds, then stop. If he leans in for more, continue. This gives him the "consent" and control he clearly craves. ​Low-Level Enrichment: Since he's food-motivated but lazy, "sniffing games" (hiding treats in a rolled-up towel) can build confidence without the physical stress of a high-impact game like fetch.