[gvand]

Take a look at yourself and identify things that you'd like to improve now that you have the chance, maybe that you never even though to be possible to improve/learn (too hard, don't have time/motivation/etc...).

And then improve them, maybe through new positive habits and routines. As other have suggested it could be your fitness level, nutrition, your ability to concentrate or to be less perturbed by external events. Or even the meta-ability to "build habits" to improve various facets of your life.