Bad habits creep up on us suddenly and then get stuck until we have no control over them. The psychology behind them is pretty simple. We unconsciously think about things and then physically do them without really having any form of self-control over them. Self-control is another basic idea revolving around this and we seem to have none when it comes to reinforced bad habits.
It's a very simple phenomenon: trigger, behaviour towards a trigger, and then reward. What is the reward? It's probably the bad habit we are unconsciously doing every time we feel a trigger emotion.
Now coming towards a few bad habits and how to get rid of them and what triggers persist around them.

1. Stress Eating:
What is stress eating? It's eating foods to make us feel better when we are stressed. But don't we consume food only when we are hungry? This is a behaviour trait for us that we assume that we feel good when we eat so maybe when we are stressed, we should continue to do so and we might feel better. This slowly turns into a bad habit and can lead to obesity.
A few ways to stop yourself is to have junk food and other unhealthy items that you crave the most out of your house. You can also have stoppers like sugar-free mint gum or a hot cup of tea which can take your brain away from the food and towards actually coping with the stress. Being mindful plays a huge part in it and if you switch to conscious decision-making while you are craving things then you can change them.

2. Nail Biting:
Nail-biting is a habit that can be related to anxiety or just simply a bad habit that almost half the population can’t get rid of. Nail-biting can cause serious infections in your cutis as well as deposit germs in your mouth which can lead to serious health problems.
If you want to stop nail biting then there are a few things you can do. First, make sure you keep your nails trimmed so you aren't tempted. You can also apply bitter solutions to your nails which are available over the counter. Getting a proper manicure may also prevent you from biting nails. Just keeping in mind all the germs and dirt particles that are constantly on our hands should stop us from nail-biting.

3. Drinking Fizzy Drinks:
Fizzy or carbonated drinks are getting very common nowadays. They are essentially caffeine drinks laced with sugar and carbon dioxide which is not a very healthy combination. They are addictive because of the caffeine but even though caffeine is not so bad in moderate quantities, soda drinks are because of the sugar and can potentially make you gain weight and leave you dehydrated.
To stop this, you need to replace your drink choice, so the next time someone offers you a soda, ask them for water instead. Caffeinated drinks are another healthier option if you do crave caffeine. When you stop your fizzy drink intake, you will start to get repulsed by it and eliminate it.

4. Not Drinking Enough Water:
Dehydration is a problem many of us face as we are not mindful of our water intake. Humans need more than 2 litres of water every day to stay hydrated and we often don't consider this.
A good way to stay hydrated is to always keep a water bottle on you. You can also make flavoured water but not with sugar just fresh herbs and lime. You can also keep reminders on your phone to drink water.

5. Staying up Late:
This is a bad habit as it disrupts your sleep cycle. You stay up at night and are tired during the day and it makes you highly unproductive.
You can stop this habit by keeping all electric devices away from you when you go to sleep as screen light can shut down all your sleep signals. Turning on a podcast on the other hand can help you go to sleep quicker as your brain drifts off slowly from the voices to sleep. Using night oils and soothing candles can also help you relax to sleep.

6. Scrolling through Social Media:
Social media is an addiction like no other, especially in present times. Not only does it affect our eyesight and brain health but also makes us less productive by wasting our time on mindless scrolling. Yes, it is a necessity nowadays and you need it to look at the current world affairs among other interests but it can get to a point where it is doing nothing but wasting our time and affecting our health.
A good way to get off it is to use apps that block your social media apps for a given time when you work. Turning your phone off and putting it in your bag or desk can also help. A thing that proved helpful was turning off notifications which can make you forget about your phone for quite some time to get the essential things done.

7. Ignoring Skin Health:
Skin Health especially your face is very important. Nowadays due to global warming, harmful chemicals, and smoke which are constantly present in our environment, there is a need to keep the skin protected at all times.
Wearing a sunblock even in winter is obligatory as even though the sun is not out as much, the UV rays index is still high on winter days. Moreover, keeping your skin hydrated through moisturizing and drinking enough water as I mentioned earlier as well as eating healthy vitamin-rich fruits and vegetables keeps your skin fresh and helps it fight the harmful toxins and bacteria that surround us.

In the end, I want to say that all these habits can be easily broken by us if we are conscious about them. Ignorance of these things is what solidifies these traits and can lead to a harmful way of living. A healthy lifestyle and habit pattern is what you create on your own by taking charge of your life.