Take a deep breath mom. He's FIVE. Do 5 year olds need goals? At 5, my son didn't want to do anything either.
Instead of thinking of him as unmotivated, how about thinking about helping him find his passion? This is particularly important for bright kids, I think, because they need a reason to immerse themselves and work harder.
Several things helped my son:
1. Time and maturity. At 5, he wanted to be able to do something now. He didn't understand the link between practice and improvement. I think it was just developmental. At 10, her certainly understands it. Last year, at age 9, he decided he wanted to play baseball. Since he was just starting, he was considerably worse than many of the kids. After the 2nd practice, the coach gave him a ball, said "take this home and throw it up on your roof and catch it as it rolls off. Do this until you make 25 catches." (we live in an area with predominately 1 story houses, so it was feasible). Darned if ds didn't go out on his own and do it. At 10, he asks me to play catch and wants to do pop flies, grounders and line drives. The kid works hard.
2. Having a passion. When he was 5, his passion was city buses. I swear that wanting to read bus schedules and destination signs on buses taught him to read. We would go down to the transit center (about a 15 minute walk) 2-3 times a week to watch the buses come and go. We'd read the schedules together. Because he desperately wanted to understand and be able to follow the schedule, he learned to read it.
3. Gentle reminders of how he has improved. Remember how last month, you couldn't even climb half way up? Look how far you've gotten now! I'm very careful to not overly praise my kids, but to focus on progress and effort.
4. Computer games. Don't flame me. Because computer games allowed him to go back and start over he learned that if he did things over and over again, he'd get better. He spent a lot of time playing "Bookworm Adventures Deluxe" (spell words to defeat opponents) in 2nd grade. It was OK if his character died. He could start over. For my son, that made him fear failure a lot less.
Now, ds still isn't as internally motivated as dd is in terms of academic things. I do have to remind the school to give him a teacher that will make him work up to his potential. If ds is bored in class, he'll sit quietly and daydream or watch the other kids. If dd is bored, she'll start telling the teacher everything that's wrong with how the class is being run. Guess which kid gets more challenging stuff?