The next thing to look at, what are the goals of the client? Many clients like personal trainers simply to help them work out, no specific goals but general overall fitness. For these clients, percentages are probably unnecessary as you as the trainer can monitor their intensity and effort by watching. If it is an athlete preparing for their sports, intensities will give you a great guideline to go by and allow you to accurately pick a weight for their work sets that will increase their potential for strength.
When presenting your business plan to an angel investor you must understand that they will be very interested in your spreadsheets and proformas, but you must also realize that it is typically an entrepreneurial optimistic approach, which causes problems with proformas. Therefore, you should have dueling spreadsheets; that is to say the spreadsheets, which take your best guess and double the time, double the expenses to compete with your optimistic approach. You should be able to present both of these to your Angel Investor; who chances are is a retired business person with a little bit of financial savvy.