Remember that every time you are close to a dog, you have a choice how to behave. You can act in a threatening or a friendly way. There is no, absolutely NO excuse for scaring a dog. Dogs are survivors. They defend themselves when they feel threatened.
By telling your dog you are friendly, it does not need to feel insecure in your presence. It can change the whole relationship to your dog.
You always have a choice. You can accept that your dog is giving you a calming signal to tell you that he is tired, or cannot concentrate any more, or that he needs a break, for example.
If you want your dog to respect you, you must also respect your dog. A good relationship is based on two-way communication, and living together in a well-balanced togetherness. Leadership does not solve anything; it only creates problems, in our lives as well as in the dogs' lives.
It is your choice.
From Turid Rugaas (1997,2006) On Talking Terms with Dogs: Calming Signals 2nd ed. Dogwise Publishing p.73