It’s so easy to become complacent when you’re not passionate.
You feel the standard at which you’re performing is good enough. You become passive and don’t push yourself. Why would you anyway? It’s not like you feel connected to the material, and when there’s no connection, there’s no reason to give it everything you’ve got.
Find your passion, and run with it. Tired feet will never be a concern, because your drive and focus will present themselves to you. Don’t be one of those bright minds that are wasted away, all because you didn’t have enough time to persistently build a niche for yourself.