Matheran is one of the great places to go trekking situated a proverbial stones throw from aamchi mumbai
i hv trekked through several routes:, garbut, regular road, cross country to Neral and from Chowk. In additional there are routes via Peb Fort & Panvel that I hv heard of.
All these treks are beautiful day climbs, especially scenic in the monsoons, though I believe them to be interesting at other times of the year too. They usually take anywhere between 3-6 hours , and are essentially easy requiring no more than some basic trekking experience.
Handy tips for trekking are available at various web-sites.. I recommend Trek the Sahyadris. I would love to give more specifics and please contact me 4 the same.
btw, these treks are for everybody, it may comfort u to know that I am 40, and weigh nearly 100kgs, and I have thoroughly enjoyed myself , none the less... only a couple of days of aching legs, nothing more :-)