The advice

1. You must train at least 3 times a week.

2. You should train at least 3 times a week.

3. You had better train at least 3 times a week.

4. You ought to train at least 3 times a week.

5. You may train at least 3 times a week.

Marius has suggested the best alternative as ' I think you should train at least 3 times a week'.

On reflection, some other idea crossed my mind.

6. I would train at least 3 times a week.

When giving advice it would be better to use the modal verb 'would'. Once Marius told me this. 

What do you think? Is the best sentence the 6th one?