I have the same experience. I could go ahead and start implementing. But that means committing to a particular design. The first design that comes to your mind is typically not the best at all, why would it be. Therefore I feel hesitant to start coding it right away. Give the design-ideas some time to boil a bit in my head while perhaps focusing on something else. The better designs then typically pop up and that saves a lot of work in the future. And eliminates a lot of unnecessary technical debt.
The key is to keep in mind what is the current problem you are looking a solution for. Then here and there while you're eating or even watching TV ask your brain the question "What could possibly be the answer to this problem?". As if by some magic it is often the case that the brain then comes up with hey maybe the solution could be found by exploring this territory further ..."
