Many students find that their speaking ability lags behind their other Spanish skills not only due to its inherent difficulties,* but also because speaking is not a solo event, so you generally need at least one other person to practice with. But not always - here are some ideas and tips for independent speaking practice.
Unless you're a meditation master, you probably have thoughts racing around your head throughout the day: to do lists, projects and plans, dissections of past discussions, and lots of ideas, both good and bad. Instead of keeping them bottled up, go ahead and talk to yourself in Spanish - at least while you're alone. You might use the wrong word or massacre the pronunciation, but speaking can help you feel more comfortable with the feeling of the words in your mouth the next time you actually talk to another person.
Read Out Loud
When you get bored talking to yourself, try reading out loud. Recite your vocab lists and travel phrases, read a newspaper article, or dive into a book. In addition to being good speaking practice, this will expose you to grammatically correct Spanish and new vocabulary. Win - win!
Listen and Repeat
Listen to news radio or watch a dialogue-heavy movie, and pause after every sentence or two to repeat what you just heard. This offers the same benefits as reading out loud, plus a bonus: you get to hear exactly how everything is pronounced, rather than stumbling over new words. Win - win - win!
No, I'm not suggesting that you sing (though you can if you want to!) Recording yourself speaking Spanish allows you to go over your constructions, word choice, and pronunciation with a fine-toothed comb. You might even be able to submit your recording to someone online who can critique your efforts. Plus, you can save the recordings in order to track your progress. Try listening to today's recording in a month or two to see hear how much progress you've made.
All that said, it's still better to talk to other people as much as possible, and not being in a Spanish-speaking country is no excuse. Find out how to practice speaking Spanish, whether or not you're in Spain and also how to practice speaking Spanish online.
*Why Is Speaking Spanish So Difficult?
Language production (speaking, writing) is always harder than reception (listening, reading) because the former is based on the latter. Unless you're reciting a monologue, speaking obviously requires listening skills: you must be able to understand what others are saying in order to respond to them. And while writing typically allows some time to think about what you're trying to communicate, speaking occurs "real time," which requires spontaneity and adaptability. There are additional production difficulties related to the three main aspects of language knowledge:
If you don't know a particular Spanish word, it's obviously impossible to produce it. In contrast, when receiving, you might able to recognize or figure it out due to context, cognates, and other audio/visual clues.
You can usually understand the gist of spoken or written Spanish without knowing the nitty gritty of the grammar used, but you can't produce grammatically correct Spanish that you don't know.
On top of knowledge of words and structures, speaking requires that you be able to approximate correct pronunciation of new sounds.
So speaking requires good vocabulary, grammar, pronunciation, and listening skills, plus the ability to answer questions, adapt to changing topics, and deal with other unplanned detours. Add to that shyness, social anxiety, perfectionism, and any number of other tongue-tying troubles, and it's no wonder that so many Spanish students have trouble speaking. By making the effort to practice on your own, your face-to-face interactions can only get better.