This is a worthwhile thing to spend 20 minutes watching. A man called Mark Bowden giving a talk at TEDx Toronto in 2013. I suppose there are lots of resources on the internet and in the bookshops about body language, but Marks talk is short, excellent and entertaining. It explains why you need people on your side in the first place. If you ever have to give a talk or present something or convince someone, this will help you.
Whatever your business is at some point it involves human beings. Making sure that they are happy and into what you do is key to being very successful. You can tick along without thinking (or caring) about the culture in your organisation but any time and effort saved will likely cost you in other ways. Recruitment, retention and managing the quality of your employees will all become more difficult . If you don’t run an organisation that people want to work for, then salary is your only weapon.