Punctuation help

Yes, you do. Regime is the ruling government. Regimen is the word to describe a fitness system. I would use 'more fit' rather that 'fitter'.

 I stuck with my regimen, and now I feel more fit than I have for ages.

Lewis, I have checked the following online dictionaries, and they all say that fitter is the correct comparative of the adjective fit: Longman Online, Dictionary.com, Oxford, Random House Unabridged.  Do you have any other sources to back up your opinion? I'd sure be interested to hear about them.  Fitter 'fits' the comparative adjective rule I teach my students, which is that a one-syllable adjective adds -er (doubling the final consonant in the case of consonant-vowel-consonant) to make the comparative, with the notable exception of fun, which is more fun. 

I completely agree with you on regimen vs. regime. 

Comma punctuation rules are so all-over-the-map, but I don't take any serious issue with your insistence on a comma in Sanjay's sentence.  There might be other opinions out there, though.