Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
if you engage in any exercise program you receive or learn about through the fitbit service , you agree that you do so at your own risk and are voluntarily participating in these activities . 

```
. OPTIONS: ['Jurisdiction' 'Choice of law' 'Arbitration' 'None' 'Content removal'
 'Unilateral change' 'Limitation of liability' 'Unilateral termination'
 'Contract by using'].