This was honestly a hard question for me to think about, and I don't exactly know what my life would be like then.
My initial reaction to the question was, I wouldn't act like a Christian if there weren't any consequences, if heaven weren't real.
However, I started to think about how I would live my life differently, and I don't really think there would be much that I would do differently. I might not feel guilty when making mistakes, but I wouldn't probably do much different.
The ultimate reason for accepting Jesus was to save me from my sins, so that I could spend eternity in a beautiful place of worship and love instead of eternal damnation, solitude and burning. However, my Christian life offers me a whole lot more while I'm still here.
When I have a problem, I get through it because I have someone much bigger than myself to rely on. I'm a natural worrier, but the only way that I can have peace and stop worrying is because I give it up, stop thinking about it and let God take care of it instead. I wouldn't really want to take on the problem's of life even if there was no heaven.
Some problems I can't take care of - illness, relationship problems among friends - I can't take care of myself. These are things that are beyond my control. However, I know that all things work together for good, because God is in control. Even if there was no heaven or hell, I still would want to believe that God was in control.
What if there was no heaven? I don't really think my life would be much different. However, I'm thankful there is a heaven so that this lifetime is not all I get. It makes life so much more hopeful.