Below are 5 major things everyone feels at one point or another and the solutions to help you feel better.
1. Complaining

Have you heard the saying "It's easier to hate someone than to love someone"? While this may seem true, it isn't. It takes an awful lot to like someone, especially when they seem to get on your nerves whenever you see them. It's even harder to accept their flaws and love them. Disliking or hating someone is easy, you don't have to work on building a relationship with them or even attempt to talk to them. While you're complaining about what they do or don't do, they're trying their hardest to show you they're capable of doing something. The next time you start complaining about something or someone, write down five positive things that out rule the negatives. I promise you will feel better, and eventually you will only see the positives in others.
2. Under Appreciated

Those insecurities you had will soon vanish, and you will feel on top of the world. Loving yourself will promote self-approval and confidence. Plus, you don't need the approval of someone else in order to feel happy and to appreciate yourself! Be a better you for yourself, and no one else.
3. Worrying Too Much

The next time you start worrying about things that have or haven't happened, sit down with a piece of paper and pen, and write out three possible outcomes that are good. When you start writing things down (whether it be goals or happy thoughts) we instantly feel more productive, and we have a grasp on our emotions. Writing has self-soothing abilities, and will eventually enhance your self-knowledge. The next time you start to worry, bring out your paper and pen and jot down happy thoughts, things you wish to happen, or just a short note to yourself. You can even start a "worry journal" where you can write down your fears and thoughts. You can reflect back on it at a later time during the day.
4. Fear of Loss

The same goes for material items. You may say "I could never lose this, I'd be so upset" and misplace whatever it is you're afraid to lose. Time will go by, and you may not even notice it's missing until the next time you think "Oh, what did I do with that?". Suddenly, your heart sinks, and you get frantic looking for your item. The scary truth that you'll have to face is: It didn't mean as much to you as you thought it did. If you truly treasured your items, you would find a good place to put them. On your desk, or in a box near your bed. You wouldn't be so careless with them! So, no worries. Material items come and go, it's nothing to get upset about.
5. Overcome Jealousy

We all fight our own private battles, some worse than others. We never truly know what someone is going through unless we're told by that person in particular. Instead of focusing on somebody else's positives and wishing your life was more like theirs, water your own grass. There is no better way to happiness than keeping your mind busy and focusing on yourself. Who cares if someone has a "better sense of style" than you do? Does style matter when you're out in the real world? I don't think so. What matters is what's on the inside!