The concern is valid; your basic plan should be to stay calm and not increase your heart rate. If other options for evacuation are not available, slowly walking yourself out is the best remaining option.
The bitten area can swell quite a bit, so remove nearby jewelry or clothing to prevent them from turning into tourniquets. If you have a pen you can use it to mark the extent of the swelling on your skin along with the time; doing this at regular intervals will allow you or doctors to monitor how fast it's swelling. (The easiest way of doing this may be by measuring the limb circumference at the bite, and at a few places further up, and recording those numbers.)
For treatment, wash the bite with soap/water, and splint it just below heart level. When bandaging it remember to not wrap around the limb in case of swelling. If you happened to get a good look at the snake, try to remember it as that will help with identification, but don't go searching for it. Finally, don't use tourniquets, ice, incisions, sucking, et cetera.
References: My answer is largely derived from Buck Tilton's Wilderness First Responder text. One might also review Medscape's Rattlesnake Envenomation Treatment & Management, but in general the treatment recommendations for pit vipers are consistent across current sources.