You only have temporary curiosity, amusement, and challenges, but that does not necessarily mean you are really convinced that it's necessary or that it's not even worth to do it. It's just a way you have to set up some kind of activities to follow your instincts or your curiosities.
If the imagination is to transcend and transform experience it has to question, to challenge, to conceive of alternatives, perhaps to the very life you are living at the moment.
Courage is resistance to fear, mastery of fear - not absence of fear. So many look to eradicate fear from their lives, when that is an impossible task. You can certainly experience moments in absence of fear, however accept that fear will be with you whenever you are in the process of living creatively. The challenge is to go ahead regardless, simply notice the feeling and manage being courageous.
Science is based on experiment, on a willingness to challenge old dogma, on an openness to see the universe as it really is. Accordingly, science sometimes requires courage - at the very least the courage to question the conventional wisdom.