Training & Nutrition - The effects of driving a bicycle taxi?

So I've just started a job as a bycicle taxi. At the same time I'm also trying to improve my speed and endurance. I'm pretty sure my endurance will get better but I'm a bit worried about the speed. I know my legs will get strong from pushing around upwards of 250 kilos all day but I'm not sure if this will harm or help me in the long run. Anyone else have any ideas? Anyone work as a bike taxi before? I'm thinking of making my ride home on my CrossCheck a bit longer(it's barely a 15 minute ride) and just pushing a low gear around for 30-45 minutes. Would that be a good cool down?
Any other tips?

I've been pedicabbing for three years now and you definitely will get stronger the more you ride. It will hurt your speed in the short run don't pedicab then race the next day, its not very fun. Why are you worried about speed; what are your goals as a cyclist? As far as a cool down an easy empty ride to the garage and your ride home spinning a higher cadence easy gear would be fine, you'll be tired and not want to ride any more. Get fifteen minutes of extra sleep instead of riding longer. Where are you working?

I don't have any serious goals as a cyclist. I like it, do it everyday, and just think it would be cool to go faster, and go faster longer, than I can now. I might try racing sometime, but for now I'm not interested in anything like that.

So you are agreeing with ***** about riding a heavy bike to get faster then huh? :))

The more you ride whether regular bike or taxi will help you get faster don't worry about speed right now just work make some money have fun and get in better shape then when you feel like it you can do speed drills. Pedicabbing helped me the most with starts in races and in time trials. If you want to ride more do a more serious ride ending a few hours before you work not after. I did cross races in the morning and worked in the afternoon and felt fine I just didn't work the night before a race.