It looks like the Amtrak Floridian stops in Lakeland before going over to Tampa and back and then heading on north or south. Can a person hop off the train in Lakeland and hang around and stretch the legs for the 90 minutes or so that it goes to Tampa and back? Or do you have to stay on the train to maintain your ticket?
If you are planning to hop off Amtrak in Lakeland to stretch your legs while the train continues to Tampa and back, there are a few important considerations.
Amtrak tickets are generally valid for the specific train you booked, and your seat is reserved for that train only. When the train stops at intermediate stations, passengers can usually get off briefly if the stop is a scheduled layover, but leaving the station and returning to the train mid-journey can be risky unless it is a planned layover long enough to allow passengers to safely leave and return. In Lakeland, most stops are short, typically just a few minutes for boarding and disembarking, not long enough for a side trip to Tampa.
In summary, while it is tempting to use a stop in Lakeland to explore nearby areas, the train schedule and ticketing rules make it impractical to hop off for a 90-minute trip to Tampa. You would be safer staying on the train or booking a separate trip if you want to see Tampa.