There are three elements that are standing between you, and what you want to draw.
The first element is time. Many aspiring artists put off developing their drawing ability give all kinds of excuses. "I don't have enough time", "I'm busy with career and family", "I'll get started when I can find the time", and so on and so forth.
The truth is, these people are never going to get started. The next day comes and go, and we still hear the same excuses. Tomorrow just never comes! Without consciously setting aside the time to draw, nothing is ever going to happen. If the artist feels that he or she doesn't have the skills (which I'll come to later), there's a need to set aside time to develop those skills. No excuses.
The second element is skills. Some people have the talent, but sometimes they just don't know it. I don't care what anybody says, but talent without development is such a complete waste. Talent is nothing without development. The more talented artists just learn quicker than others, but still, without guidance and direction, it's all for nothing.
So how do we know if someone has the talent? Nature has its way of revealing that to the artist some way or the other. I want you to think hard from some past events in your life. Have you ever drawn or sculpted something naturally and it just came out looking good? Maybe not great yet, since the talent has not yet been developed but good enough. Any incident at all? If you have such memories, chances are, you have the talent without even you knowing it.