People need to be pushed. This weekend my Greek students will be pushing themselves to master chapter 18 of our grammar. They will work themselves to the bone. I do not feel comfortable asking them to do something that I'm not doing myself. My work is not to master New Testament Greek but to master the art of lifting.
As with learning Greek, once you've put in the initial effort, you'll start settling into a routine. You'll start to see tangible results, and that in turn is going to increase your motivation further and you'll really start enjoying the process rather than seeing it as a chore.
For me personally, I look forward to my gym workouts as much as I look forward to getting back into the classroom to teach. That's because I'm developing the habits of proper training and nutrition.
If you can learn to appreciate the effects your weight training and diet have on your mind and body, then it's something you'll enjoy a good amount of the time.
When I took first year Greek, I absolutely fell in love with the language. I learned to enjoy my studies of the language and I wouldn't have wanted it any other way. So my advice to you would be: If learning a language or improving your health is a goal you'd like to strive to accomplish, just go for it. Get started, grind out the initial stages, and you'll find that after awhile you get into a groove and it's fairly smooth sailing.
Bless you as you chase down your goals.