I'm 41 and got dumped. It's not going well.

I'm 41 and my girlfriend (39) of 5 years broke up with me suddenly 3 weeks ago. She said she doesn't think we're in love and she needs time alone. Up until this happened, she's always bragging about how I'm a good man and how I'm a genuinely nice guy. But its becoming more and more obvious that shes not coming back. It's been a real struggle that has forced me into tears several times. Keeping my distance and respecting her space has been the hardest thing I've ever had to do. Everyone's advice is just "focus on yourself" or "move on" or "work on making yourself better". Those words mean nothing to me at this point. I actually don't know what im supposed to be doing to improve. I go to the gym several times a week since the break up. I've dropped 20 lbs. I have a pretty good job. What have you guys done after a break up to get over it? What does "focusing on yourself" really entail? Im alone ALL the time. Please help because nothing I do seems to help my broken heart. Thanks in advance