An adventure travel need not be expensive. In most cases, you would not be staying in five star hotels, eating in fancy restaurants and taking limousine rides. Instead, you would probably be staying in guesthouses, eating at local food stalls and taking public transport. These usually more than help to hold the line on the total cost.
If you need more reasons to start your adventure travel, here are some motivating quotations I have collected.
Now, are you willing to join in adventure tour?