It took me years to finally get in a solid routine at the gym. There is some truth in saying you have to force yourself sometimes. The main thing I found that helped was having a solid partner who would go with me. We can always count on each other to be there after work and that makes it a little more fun. Once we got in that routine it was made more fun by watching my progress. Going from 25s to 45s on chest press, or 70 to 100 on tricep press, picking up protein shakes, gaining 30 lbs.. point is, it requires a lot of patience. Once you get there, it is definitely worth while.
With that said, it is not for everyone. Exercising sucks, no matter how you look at it. Those are just pointers I offer that I found personally helped me learn to enjoy the gym.
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If Jesus died for my sins, then I should sin as much as possible, so he didn't die for nothing.