(Image credit: Getty Images) Risk is a natural part of investing, and indeed, volatility is the price of admission to building long-term wealth. This is what Ben Carlson, director of Institutional Asset Management at Ritholtz Wealth Management, reminds us in his new book, Risk & Reward. "Risk does exist in the market, and if you want to earn a return on your capital above the rate of inflation , you have to step out and take some risk in some form," Carlson told me when we sat down to discuss his book, which goes on sale on May 12. "And over the long run, that risk has been rewarded and I think it still will be rewarded." In other words, he says, "risk and reward are attached at the hip." From just $107.88 $24.99 for Kiplinger Personal Finance Become a smarter, better informed investor.…