I think u go for harder workouts initially that makes u feel like this. Go for easy ones ,gradually and at low pace move to harder ones.Moreover its about mindset keep urself cool don't look for results at once. It takes time. If u see the results then nothing can stop u.Go on with what u do and love to do it.
Ana I am 46 yrs.Daily I do my workout for more than 2 hrs. 15 mints walk, 10mnts running, jump rope 200 ,squats 50,push ups 50,abs and core 20 mints and thum bells for 15 mints. What more can u expect for my age.If u r younger than me this is enough to motivate u.Just love to do ur workouts nothing is impossible. Good luck.
Fine why waiting for something to happen do something to happen. Feel free and start today u will b rewarded tomorrow. Have nice day and enjoy ur every today with good workouts feel the glow and brightness spreading in ur face and body.