Verb
1. persist
2. continue
4. go on
5. keep on
6. keep going
7. struggle on
8. hammer away
9. be persistent
10. be determined
12. keep at it
15. be tenacious
16. stand one's ground
18. hold on
19. go the distance
20. stay the course
21. plod on
22. stop at nothing
23. leave no stone unturned
24. soldier on
25. hang on
26. plug away
27. stick to one's guns
28. stick it out
29. hang in there