Believers look forward to the future glory of becoming like Jesus. It is a glory so great that our longing for it is described as "groaning." This passage (Romans 8:23-25) answers three questions about this groaning:
1) What prompts our groaning? (The Holy Spirit)
2) What are we longing for? (the redemption of our bodies)
3) How do we long for it? (faith-filled, eager hope)