I haven't sifted through the whole thread, so i don't know if this has been mentioned, but some very common things I see inexperienced riders do, that slows them down and takes some of the fun out, is riding with a dry/dirty chain, not having enough air in the tires, and having the seatpost misadjusted (usually too low).
So, lubricate that chain, almost any lubricant will do (doesn't have to be some expensive bike-specific lube).
Also, consider getting your own tire pump, they're worth their weight in gold !
And finally, get some help with proper seat height. If nothing else, watching a few you-tube tutorials is usually very informative and helpful, for a great many bike issues.