What works for me is blocking time in my calendar. Also this makes you aware of the limits that your life is currently imposing (sleep, work, family, friends) and what you can achieve or not. Like, trying to get to run from 0 to 10k while dedicating only 1 hour per week will not guarantee to get you there in 3 months.

Consistency is key, so I believe that the best resolutions are those that can be turned into habits.