In an ideal world, a primer on feeling good just wouldn't be necessary.But thankfully, the jubilantly goofy Todd Parr knows that we could all use a tipor two from time to time, no matter how old we are.Just as he did in Do's andDon'ts, The OkayBook, and his other titles (16 and counting), Parr keeps it supersimple, with fat lines, bold colors, and a repetitively cheery, often sillymessage. His words get some smiles here and there ("Brushing your hair...