I saw the trailer and it looked intriguing. I tried coming up with some ending scenes, but could still not pinpoint something that may fit the movie. I thought he was a former drug dealer who sold 7 pounds of crack and was willing to give away the money, but I don't think that fits quite well. For the heck of it, I just did a little searching and found out a likely scenario for the ending.
Source
Source
The M. Night Shyamalan ending
Premise: Ben is really a ghost.
Chances: None. As Ms. Dawson said during the Oprah Winfrey interview, she thought Seven Pounds was going to "have some weird M. Night Shayamlan ending," but was happy to be proven wrong. Sounds like somebody didn't like The Happening.
The Hancock ending
Premise: Ben is really a superhuman immortal that has been married to Charlize Theron for the past 3000 years.
Chances: None. However, that is the way Hancock actually ended. For real. And the scary thing is... it actually worked! Just file this under further proof that Will Smith can do no wrong.
The likely ending
Premise: OK, deep breath! Ben killed seven people earlier in his life (we'll assume while drunk driving). As punishment, he decides to commit suicide and donate his organs to seven people who really need them. However after he falls in love with Emily, he has second thoughts about going through with the plan. Ben tells Emily his true motivations and she predictably freaks and dumps him. Crestfallen, he realizes the best way to show Emily that he truly loves her is by giving away his heart. (In this case, literally.) Ben dies, allowing Emily to live. Cue the waterworks and poignant Rosario Dawson voiceover!
Chances: Very high. We don't mean to toot our own horns, but we think this scenario seems incredibly plausible.