It is a trade between comfort and security. At first I had it much too loose, but it was all I could take when I first started. Over time I was able to get it much tighter, with virtually no wriggle room at all... It took many months and a lot of adjustment to get it just right. If you have it too tight to begin with the straps just cut into your waist. Over time your body gets used to it and you can tighten everything up.
