Why is it so difficult to learn a new language?
As with anything, learning a new language is easier for some than for others. Some people are born with an innate ability to understand and learn languages, just as some are great with numbers.
You also have to consider age. I think it is much easier to absorb language when we are toddlers. But don't be discouraged. Even for children, the process still takes years before a child speaks in full ineligible sentences. Even then, their conversational skills are far from being fully mature.
The bottom line is, you should not become easily frustrated. To be fluent in any language usually takes time. Little children are not frustrated at how difficult it is to speak. They do the best they can and improve as people correct them or as they understand better. The same can happen for you. Instead of thinking about all you don't understand yet, marvel at what you have learned and keep practicing. One day you will out grow your Spanish baby talk.
Because you if you ask the question "Why is it so difficult?" you find the answers to "Why is it so difficult?". How about asking "How can I make it fun?"
One of the things that makes a new language difficult (especially as an adult or near-adult) is that you need to unlearn some habits that you picked up with your first language. This does not mean unlearning/forgetting your original language but many/most people while learning their first language, develop the habit of thinking that it's the best/only/logical way to say something and then get frustrated when the new language "works" differently.
My guess is because language is just a way of communicating one's thoughts to another, and learning a new language requires some rewiring in the brain as you need to learn how to communicate those thoughts differently than you do now, which can take a good amount of time.
On top of that, most people are less willing to appear foolish in front of people, as they don't like feeling embarrassed, which leads them to playing safe and not trying to improve what they need to work on.
It was probably hard for you to learn your first language too... it probably took years, you probably had great resources in allowing you to reach the level you're at now (school, teachers, and years of reading/writing exercises in your classes). You've probably clocked up thousands of hours practicing it.
It was just longer ago, so the language you're learning now, being more recent, has challenges that are sticking more in your memory
Because you are no longer 2 years old with a blank slate, a desire to communicate, and 2 private tutors (mom & dad). Now you get distracted by other things going on around you.
You are in the habit of English (I assume) and how the sentences are structured in English along with idioms and such that you have heard all of your life. When you learn your first language, you have to break that pattern of the sentence structures and pronunciation, etc. I hear the 3rd and 4th languages are easier since the habit has already been broken.
But don't think about what is difficult about learning Spanish-- think of the fun, the excitement, the rewards of learning a new language and the feeling you get when you can communicate with someone and understand enough to not only listen but also speak. Believe me, learning Spanish is much easier than you think... You may not realize it now, but it is.
It's because in every language except whichever one you learned first, everyone talks way too fast! hehehehe
Because when you are talking in your first language it is lke second nature. You process your thoughts in that language. When you want to speak in the new language you think ok this is what I think now I have to translate. Also all the exceptions in the new langauge is obiviously new and the ones in your first language is like "Duh.'
Learning a new language- like any new skill - can be a complex and time consuming process at times and the ease with which people are able to learn and retain new information will vary from person to person Learning a new language is much easier when you are a child and that is not only because we are able to absorb and retain information more easily at that age but also because young chldren seem not to be conscious of the process of their learning while they angaged in it and have NO agenda to reach a certain standard by a particular time. We adults often set targets for ourselves - sometimes without being aware of it - and then feel we have failed when we don't achieve a, b or c by a set time. Adults are invarably more self conscious about their mistakes and often scared to apply what knowledge they have in real life situations for fear of looking stupid if they 'get it wrong.' Making mistakes is a vital part of learning. We don't fail when we make mistakes we only fail if we don't learn from our mistakes and keep on making the same ones ! The most imortant factor in learning langauges is really the 'Exposure factor' Nearly all people learn much more quickly and effectively in an environment where the langauge is being constantly spoken... which is why young children pick up their home langauge/mother tongue so quickly! So if you can live in the country of the language you wish to learn you will probably learn to speak it more than 3x faster than if you were attending a spanish class once or twice a week.
In addition, some people have a natural gifting with languages like some are gifted artistically and others musically. Most importantly the willingness to persevere in the face of dificulty and discouragement and learn from your mistakes and even laugh at them will ensure that you continue to make progress.