3. I have started this hobby for three years

1. Collecting tree leaves from different countries is interesting (rewrite the sentence)
It is  interesting to collect tree leaves from different countries.
2. I/think/ you/ take up/ jogging/ because/ it/ suitable/ health condition
=>I think you should take up jogging because it is suitable for your health condition.
3. I started this hobby three years ago. (rewrite the sentence)
I have this hobby for 3 years.
4. I find making model boring because
=>I find making model boring because it takes lots of time.