I got my placard when I was 42, also. I'm now 62 and it has been wonderful to have. I used to go to the mall and if there wasn't a place close to the doors, I would turn around and go back home. There was more than enough walking in the mall. I didn't need to park out in the boonies and do all that extra walking. I use it when I need it. If there are places fairly close, or if I'm having an especially good day, I'll park in a regular space.
People will look at you but ignore them. They don't have a clue what your health issues are and they aren't walking in your shoes. Remember, your doctor would NEVER have approved the placard if he didn't think you needed it. I'm glad you got that assistance.