Mistakes while learning

There will be times when you have people above you (a boss) or even next to you (a coworker) that will get really irritated with you for "ruining" something "crucial". Errors are bound to happen when you have on your training wheels. Even if you make mistakes and get a slap on the wrist, persevere and push on. You do not need to be embarrassed for learning from your mistakes.
Food choices
People are different and have different taste buds. Whether it is healthy or not, food is a choice and it is a part of life. It is simply a personal choice that people make for their own reasons. You do not need to be embarrassed for food you do or do not like. Tell them, "It is a personal choice I have made, and I am committed to it."
Your past
Allowing positive experiences to define, confine, refine, and outshine you may cause you to be caught up in the past and unable to truly live in the present. Whether your history is positive, negative, or somewhere in between, don't hone in on the negative experiences and let it reflect your current behavior.
The cleanliness of your car/home/work space
When everyone gets in the car, you realize your Starbucks bag are still on the floor. So what? Think about it this way: everyone has a "messy" aspect of their life. Maybe their home is spotless, but the relationship with their spouse is messy. Someone's car gets washed once a week, but his/her work life could use some help. No one on Earth lives a perfectly "clean" life in every aspect. We don't apologize to others about our personal pitfalls. By being outwardly embarrassed, it only brings more attention to the fact!
Putting yourself first
If you find yourself saying no to something or making up lies to get out of it, tell them the truth, and don't apologize. You will feel much better in the long run if you are honest with them and yourself. If you're not up to a voluntary obligation, you don't have to be. You can politely deny the person's request. It is okay to be selfish from time to time. Put yourself first.