This one comes with some caveats. For instance, if you already feel bad, or have a history of chronically feeling bad, putting yourself in this space intentionally might not be healthy. It would be like overworking your muscles at the gym (which has the opposite or negative effect). With the gym, there can be a lack of motivation because we have emotional resistance, OR because our body legitimately needs to rest. We have to be tuned in to what our body needs. Same with our emotions.
A couple alternate practices can be visualizing "What's the worst that can happen?" Sometimes we dread the worst, so we avoid it. But if we really consider the worst, What if we start our business and it doesn't take off? Well, then it doesn't take off! There are truly worse things in the world. Following this question to the end, we'll pick ourselves back up, learn from our experiences and grow as human beings.
Also, "What will happen if..."? What happens if we never tell someone we love them, or don't tell them often enough? They may never know. Imagine not writing in your book, day after day. It just never gets done. And as you point out, What will happen if we never start our business? We'll live with a sense of regret and failure, just because we gave up before trying. We may lose the opportunity to tell our loved ones that we love them.
While these exercises might not dredge up "feeling bad", the mental exercise can actually talk us into doing the things we wish we would.
Some people may need to practice feeling good, instead. It trains the mind and body to accept the possibility of good things happening as a result of our actions. Again, we should tune in and give ourselves the practice we need to bring about our desired goals.