I don’t feel like it!
First of all, acknowledge that it’s okay sometimes not to feel like doing something. Then, focus on what you can learn from this particular task you don’t feel like doing. Take, for example, working with an Excel spreadsheet. It might take some time and effort to get into it at first. But then it might help you deal with similar tasks more easily and more quickly in the future. So don’t focus on the problem, but on the solution and the benefits. By doing so, you’ll create a sense of self-efficacy that will evoke positive feelings and increase your motivation in general.