I am planning to go to Goa. The only catch is I have no money.
How can I manage to do this? Taking lifts from trucks comes to mind but I have no idea how to go about it?
Let's get realistic, even if you do whatever other people may say, humans need food and a place to sleep, so absolute free travel is impossible, unless you walk (using your own energy), beg (ask for a lift) or steal (travel without ticket in a train and pretend to have no money to any ticket checking staff, which is highly highly discouraged).
Having said, and considering the total distance of travel to be 4300 kilometres (up and down) that let me try to get as close to that as possible. There is a train called Goa Express (Indian Railway Train No. 12780 at the time of writing), a comfortable sleeping accommodation on this train would just cost you Rs. 780 ($13), this would ensure that you get two full night's sleep (cant compare that to any hotel around the world), up and down you would actually pay just $26 on this.
Lets get even more frugal, if you travel by the un-reserved compartment in this train which should cost you Rs. 440 one way, this way you are assured of safety at night however no meaningful sleep is possible, this would be approximately Rs. 880 i.e. $15 for this.
If you want to demonstrate some kind of a world record for this, you can actually try to combine multiple passenger trains to reach the destination, which would involve hardships like dragging any luggage (why don't you sell the luggage to get some money, huh) and extremely tightly packed compartments involving fights (both verbal and physical) to obtain a right to sit (forget sleep). A legal travel for the entire distance on a passenger train would be about Rs. 250 ($4) and hence two way travel would be Rs. 500 i.e. $8, it would be actually tough getting a passenger train ticket for this distance as the staff may argue that there are no direct trains which you have to solve by probably showing a full schedule of your travel (if this question was not hypothetical).
I've read a report at russian-language travel forum from a guy, who hitch-hiked through almost all india, so it seems to be the only option you have
I have hitch-hiked from Mumbai to Pathankot, so from my experience -