Learning to speak a Spanish can be daunting, especially for people who start learning after the sensitive period, the time of life (generally) before puberty, when humans are hardwired to acquire language.
Most people who pick up a new language won't reach native-level proficiency. Ask any language teacher and you'll find that, although we believe that anyone can become fluent in another language, we acknowledge that most will fall short of becoming a native speaker. Those that do reach such heights are few and far between, and are extremely dedicated in their pursuit of fluency.
That's not to say that you can't make incredible progress toward that end. If you are willing and able to put in the time and effort consistently, day after day, you can make substantial progress in a relatively short amount of time.