Boredom, distractions and the mind numbing routine of doing the same thing all the time derails fitness. It is hard to get fired up about the same 3 mile loop or circuit. It is also hard to get excited about doing Fran for the 90th time. Variety is a great way to keep training interesting. Vary intensity, time and type of workout and it can be keep you going longer. Set goals and milestones to maintain motivation. Pick events to train for, benchmark workout goals and special events to help keep you excited about training. A thruster will always be a thruster, but a thruster for a specific reason is different.
What are you going to do with your fitness? Producing exceptional work capacity is what we do. For what? We all want exceptional health and a long high quality life. The horizon for the life long goal is really hard to be passionate about. More immediate horizons are needed. Make one month, 3 month, 6 month and 12 month goals. Schedule events. Schedule metrics that you can work to achieve. If you are having a hard time getting to training, make a certain number of workouts for the month a goal. Something to get excited about.
Regardless of what you decide you want. Find a way to stay excited. Stick with it. Find something in it to keep you motivated. Work on a skill to master. Work on hitting a strength milestone or lift to hit a personal record. Find a way of getting there.