Some of these have been shared on Facebook by my friends or I have found them on Google search, so unfortunately I don't necessarily know the sources. Let me know if you do and I'll add them here.
http://www.leanitup.com/wp-content/uploads/2012/05/8444318021709078_dUPWSc2f_c.jpg
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjY0p055O0rjsHTL6Pcs1Eo6Qs00AI6hg9mg0FhyQu6cWdsJ40zAjnq-GDIXRoh3BlfjfnLfeLUuRKAL-7OIUeZqyaJFEosKX17xoFr8OWexA6k0NR-gEyH-Mq7hLtMtx3xs4bgAEdbeDA/s1600/sweat-it-out.jpg
http://www.bodyhack.com/blog/wp-content/uploads/2012/03/should-i-workout-today.jpg
http://www.bodyhack.com/blog/wp-content/uploads/2012/03/regret-that-workout.jpg
Keep smiling! And keep exercising!