http://chat.stackexchange.com/rooms/324/the-locker-room

However, I don’t think you should be re-evaluating goals whenever you start not feeling like doing your current plan (because it’s getting difficult, or because you’re not seeing the progress you expected). Instead, you should be re-evaluating the plan, if you were confident in the goals at the outset. If you have accumulated some injuries, perhaps an adjustment to your between-workout recovery activities will be necessary. If you are not progressing, perhaps an increase in intensity or frequency will be needed. But, we shouldn’t just change goals to match what our lazy selves would rather be doing. Pick a goal, and stay laser focused on it. You can (and should) re-evaluate your goals, but not because you’re falling out of your current plan to get there.

Variety that is not necessary can detract from achieving goals. A couple of examples… A powerlifter who randomly decides to take up running and rowing would see their recovery between lifting workouts be negatively affected. A college athlete who has very limited time should take a super focused approach to training, finding a simple (and simple doesn’t mean easy), consistant training program that augments their sport-specific practices and workouts.

Switching things up due to boredom isn’t training and wastes time. Throwing in a variety of different exercises just because some are fun isn’t training and wastes time. I think the same thing goes for anyone with a busy schedule. Keeping things consistent allows exactly what you’ve advocated: goal setting and tracking progress. The fun will come later, when you’re doing things better and faster than the opponent, finishing a long hike with tons of energy to spare, or biking with your tent to a far away place… whatever it is you’re training for.