In elementary school, you think "I miss sitting at home and eating snacks and taking naps." In high school, you think "Middle school was a breeze, I wish I could go back." In the real world, you think "College was the best four... five... six... years of my life." If that's the thought that's going to follow you around for the rest of your life, you better make sure you at least did it right. This is why it's okay to take more than four years to earn your degree.
College is an important part of your life. It's a lot more than going to class every day. College is where you get to experiment, explore, and figure out what you're good at and what you like. College is where you learn about life and unfortunately, sometimes in life, you need to sacrifice. If that sacrifice happens to be pushing a class or two back a semester in order to join a fraternity, that's okay as long as you're happy! If you decide that you need another semester so you can express yourself in an art show, or another year so you can play football, do it! And more power to you if you're extending your school time in order to pick up a minor or a double major.
College is your time to set goals for yourself. If you want to leave college with a mechanical engineering degree, that's awesome. What does it matter if it takes you four or five (or even more) years to do it? Unlike high school, no one is going to judge you for taking an extra year to complete your necessary requirements. Or an extra two years. Or three. Or however long it takes for you to fulfill your accomplishments. This is your time to grow.
I know that it's easier said than done but you can't allow other people's opinions to cloud your vision. Whether it's about what makes you happy or how long it takes you to get there, nothing matters except how you feel about the situation.
Another reason it's okay to take more than four years is because life happens. College is meant to help you, not hurt you. It's okay if you can only go to school part-time if you're working to pay for your education. I know from experience that family emergencies can set you back a semester or so, and believe me - it's not the end of the world if you fail a class (It's actually quite common!). You should always focus more on your mental health than feel pressured to finish college in the suggested time frame.
Basically, you shouldn't freak out if you need to take an extra semester, or even a year or two. College is supposed to be the best years of your life, no matter how many years it takes you! There's no need to stress it. Just relax, take a deep breath and remember - there's always next semester.