what i am doing on https://herbert.poul.at is to generate two .html files every 4 hours and include them in the website ..
i have attached my simple example script (it assumes you have the CPAN version installed http://search.cpan.org/~hpoul/GPS-Garmin-Connect/ )
you need to modify config.pl to include your username/password from connect.garmin.com .. and then execute it in the local directory using something like:

cd path_to_scripts

./fetchdata.pl > /tmp/fetched.json # this will download a simple json object containing all runs

./parser.pl /tmp/simple.html /tmp/detailedfile.html < /tmp/fetched.json

the last command generates a "simple" and more detailed html output .. which i include on my website (the simple one is displayed in the right column, the detailed is the one you see at https://herbert.poul.at/wiki/show/Running/ )
there is no templating magic or anything, so to modify the output .. you need to modify parser.pl directly ..