Give It A Month
If you are consistent and you build your running sensibly, it will take you about a month to start feeling noticeably more comfortable when you run. It’s important to know this and set your expectations accordingly when you begin a running program. Going in with unrealistic hopes of getting fitter within a week will only set you up for discouragement and quitting. On the other hand, you’ll have an easier time sticking with it if you know that getting over the hump will not take longer than about four weeks.
Take a “no excuses” mentality into your first month of running. Don’t miss a single planned run for any reason, no matter how much you dread the next one. If you do this, you will progress at the maximum rate possible and find yourself enjoying your runs after four weeks and no longer needing to psych yourself into doing the next run.