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In terms of Implementation, a large portion of our work was done using Jquery and Jquery-UI Widgets. This is due to the simplicity of our actual idea, and most of it could be captured with Jquery-UI's Datepicker. One limitation of it however was the ability to gather ranges of dates. In order to get around this, we had to convert the dates into Unix Timestamps, and increment the start Date by the milliseconds in a day and then parse it with Datepicker to revert it back to a calendar date. We do this for the results page to properly grab all workouts in between two dates. This was particular particularly difficult and ended up taking up a large amount of time to figure out and fix during GR5.
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"Prototypes are a designer's best friend" - Instead of trying to implement everything immediately, an iterative design process involving multiple partially functional prototypes helps isolate specific issues, and gets many of the big things out of the way by the time you want to focus on details. The benefits of prototyping vastly outweigh the costs (if you are reasonable about how you go about it).
"Vast changes may be the easiest most effective direction" - Getting too attached to an idea can bog you down. If too many users take issue with something, even if it's a big component of your design, it may be best to scrap it and try something completely different. This is related to users always being right, but just because a design idea is important to you, it isn't necessarily a good idea for you to keep.
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