Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
if you have a medical or heart condition , consult your doctor before using the fitbit service , engaging in an exercise program , or changing your diet . 

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