Would you prefer to focus on building your strengths or improve your weaknesses?

I would prefer to focus on strengths rather than worried about the weakness.

Because I believe in positive approach as it will result focusing more on achieving success and will result in removing worry about the failure and eventually helps in building more strengths.      

I think I should work on improving my weakness so if I succeeded in improving it this will lead to an extra point of strength and by sequence this will build my strength., thanks..

I would say this would be complimentary. If you improve your weakness, you may turn it out to be a strength. 

Further, I would prefer improving weakness will pave way to increase your confidence which will be another important strength as a person in what ever task you do.

Improving the weaknesses will automatically strengthening you, so preferring improvement. Thanks.