If you’re close to your boss, have a chat with him / her. Start off the conversation by saying how much you appreciate having a job in your company, and that you really enjoy it. Slowly segue into your career path, and mention that you’d like to take on something more challenging.

Alternatively, if you’re not close enough to your boss to have these sort of chats, you can be pro-active in taking on additional assignments or helping your colleague out with their projects. Hopefully, your enthusiasm won’t go unnoticed, and your boss might start delegating more work to you. Just remember not to neglect your current duties.