To your insecure pup, the world is full of cruelty and awfulness. Those scary thunderstorms, terrifying shadows and strangers he encounters on walks keep him cautious and fearful much of the time. Dealing with his insecurities means taking a kinder and slower approach to training and everyday life than you would take with a confident canine.
Show your pup plenty of love. You want your pup to feel comfortable, safe and at ease when he's around you and your family. Although he might have plenty of insecurities outside the protective walls of your home, he shouldn't be scared inside. That means you and your family need to spend plenty of quality time with him. Play games, give him treats for being good and never yell at him. If he sticks his nose near your plate when eating dinner, it's better to distract him than yell, "no." Sensitive, insecure dogs often freak out and hide when yelled at.
Set him up for success. Anytime your insecure pup fails at something, he probably becomes distraught. He's already low on confidence, so failing just saps him of everything. Prevent him from getting in trouble and making mistakes by dog-proofing your house and training him in basic obedience. When it comes to persuading him to take a big step in the face of one of his fears, start out slow. Say he's afraid of taking a leap onto your furniture. Start out by wagging a treat in front of him while sitting on the couch rather than your bed. If he jumps, he's probably going to make it onto your couch, and he'll have more confidence to do it again. If he tries to jump on your bed, which is likely higher off the ground, and fails, he may just say "forget it."
Give him hiding places. You're not going to turn your pup's insecure personality around in a day, a week or a month. In some cases, it will persist in some form throughout his entire life. Instead of preventing him from seeking shelter and hiding in certain situations, let him be. Keep the bathroom open if he prefers hiding in there, or allow him to sit in the corner during a thunderstorm. He needs a place to feel safe in when he's afraid and unsure of things. Taking that away from him doesn't address the root of the problem, and it can make him way more stressed out.
Avoid your pup's deepest fears, or counter condition him. Getting him to jump on the couch if he's afraid of jumping is one thing, but confronting a deep-seated fear of other dogs is another. The latter can cause extreme stress, and in some cases, aggressive behavior. It's better to just walk away from the dog or whatever other stimuli causes his negative reaction. You can counter condition him, but with any type of fear that results in aggression, it's best to talk to a qualified trainer.
Be the leader he needs. Your pup takes cues from you. If you rush over to him and grab his collar when a person walks past your window, he thinks that there's something to be afraid of. If you tense up, subconsciously try to block his view and tighten the leash while encountering another dog on a walk, he thinks something's wrong. Show the same type of confidence you want your dog to show. By doing so, you'll show him there's absolutely nothing to be afraid of.
Stick to the old, boring routine as much as you can. If you take your dog for a walk every evening, feed him twice a day, crate him at a specific time of night and so forth, don't stray too far from the daily regimen. Throwing out an old routine might jump-start your week, but it can ruin your dog's. Insecure dogs love when things stay the same. When something new is introduced, it's scary!